| evidence for an early appearance of modern post-switch isotypes in mammalian evolution; cloning of ige, igg and iga from the marsupial monodelphis domestica. | in birds, reptiles and amphibians the igy isotype exhibits the functional characteristics of both of igg and ige. hence, the gene for igy most likely duplicated some time during early mammalian evolution and formed the ancestor of present day igg and ige. to address the question of when igy duplicated and formed two functionally distinct isotypes, and to study when igg and iga lost their second constant domains, we have examined the ig expression in a non-placental mammal, the marsupial monodelp ... | 1998 | 9754561 |
| skeletal fiber types and spindle distribution in limb and jaw muscles of the adult and neonatal opossum, monodelphis domestica. | the south american opossum, monodelphis domestica, is very immature at birth, and we wished to assess its potential for studies of jaw muscle development. given the lack of prior information about any monodelphis fiber types or spindles, our study aimed to identify for the first time fiber types in both adult and neonatal muscles and the location of spindles in the jaw muscles. fiber types were identified in frozen sections of adult and 6-day-old jaw and limb muscles by using myosin atpase and m ... | 1998 | 9713989 |
| [solar radiation and melanomas--is there any doubt about the connection?]. | arguments for and against there being a connection between exposure to solar radiation and cutaneous, malignant melanoma are reviewed. recent experiments with animals and epidemiological observations provide relatively strong arguments that solar radiation causes cutaneous, malignant melanoma. furthermore, epidemiological data from norway and australia support the assumption that uva-radiation plays a significant role in melanoma induction; this is in agreement with data from experiments with xi ... | 1998 | 9691798 |
| the complement system of the marsupial monodelphis domestica. | the activation requirements and pathways of the serum c' system of the marsupial monodelphis domestica were characterized using standard hemolytic procedures. the existence of distinct classical and alternative activation pathways was established on the basis of their ionic requirements, hemolytic capacity at different temperatures, kinetics of hemolysis, and differential susceptibility to the classical pathway inhibitor carrageenan. for the most part, the activities of these pathways were influ ... | 2005 | 9639092 |
| opossum (monodelphis domestica) terminal deoxynucleotidyl transferase gene. | | 1998 | 9553155 |
| fine structure and development of dorsal root ganglion neurons and schwann cells in the newborn opossum monodelphis domestica. | the aim of these experiments was to determine the state of maturity of dorsal root ganglia and axons in opossums (monodelphis domestica) at birth and to assess quantitatively changes that occur in early life. counts made of dorsal root ganglion cells at cervical levels showed that the numbers were similar in newborn and adult animals, approximately 1,600 per ganglion. in cervical dorsal root ganglia of newborn animals, division of neuronal precursors cells had ceased. the number of axons in cerv ... | 1998 | 9624588 |
| transient, high levels of snap-25 expression in cholinergic amacrine cells during postnatal development of the mammalian retina. | in the present study, we have examined the development of cholinergic amacrine cells in the retina of the brazilian opossum, monodelphis domestica. an antibody directed against choline acetyltransferase (chat) revealed that chat-like immunoreactivity (chat-ir) was first observed at 15 days postnatal (15pn). by 25pn, chat-ir identified two matching populations of amacrine cells in the inner nuclear and ganglion cell layer. bromodeoxyuridine birth-dating analysis coupled with immunolabeling with t ... | 1998 | 9579400 |
| the development of synaptophysin-like immunoreactivity in the lumbosacral enlargement of the spinal cord of the opossum monodelphis domestica. | the presence of synaptophysin in the lumbosacral enlargement of developing opossums, monodelphis domestica, was studied immunohistochemically at the light microscopic level. in newborn, synaptophysin-labeling was observed in the presumptive white matter, presumably in growing axons, and was scant in the ventrolateral gray matter. over the next 3 weeks the labeling filled the gray matter following a general ventrodorsal gradient. labeling was found in the white matter until the fifth week. synapt ... | 1998 | 9555018 |
| v(h) repertoire of a marsupial (monodelphis domestica). | when contrasted with information available for placental mammals, very little is known about the development of immunocompetence in marsupials. marsupials, however, provide interesting immunology problems, since most appear to be born at a stage of development much less mature than that of placental mammals. to further understand the marsupial immune system, the ig repertoire of the short-tailed opossum, monodelphis domestica, was characterized. the majority of the v(h) clones were isolated in a ... | 1998 | 9551979 |
| degeneration of tooth germ in the developing dentition of the gray short-tailed opossum (monodelphis domestica). | the aim of this study was to examine the developmental aspects of the dental lamina and the tooth germ of the marsupial opossum (monodelphis domestica), and to clarify the dental formula of this animal. specimens were 12-, 16-, and 18-d-old opossums. 3-d reconstructions were constructed from frontal serial sections. in these animals, the tooth germs of the deciduous maxillary and mandibular canine, deciduous third premolar and first molar, and the deciduous maxillary first incisor and second mol ... | 1998 | 9541264 |
| the acute phase response of plasma proteins in the polyprotodont marsupial monodelphis domestica. | in eutherians, patterns of plasma protein levels in blood change during the acute phase response to trauma and inflammation. until now, such an acute phase response has not been characterised in a noneutherian species. here we describe the acute phase response in a marsupial species, the south american polyprotodont marsupial monodelphis domestica, after brain surgery or injection of lipopolysaccharide. several days after brain surgery, transthyretin was not detected in plasma. for 48 hr followi ... | 1998 | 9530819 |
| postnatal development of leydig cells in the opossum (monodelphis domestica): an immunocytochemical and endocrinological study. | this study involved characterization of leydig cells of the opossum monodelphis domestica, functionally by immunocytochemical identification of the enzyme 3 beta-hydroxysteroid dehydrogenase (3 beta-hsd) and by measurement of testosterone levels using ria. immunostaining for 3 beta-hsd was first detected in a few leydig cells on day 16, was increased by day 24, reached a peak at 4 mo, and was present even in senescent (3 yr) animals. plasma testosterone was first measurable (0.35 nm) at prepuber ... | 1998 | 9510954 |
| development of walking, swimming and neuronal connections after complete spinal cord transection in the neonatal opossum, monodelphis domestica. | development of coordinated movements was quantitatively assessed in adult opossums (monodelphis domestica) with thoracic spinal cords transected by (1) crushing 7-8 d after birth [postnatal days 7-8 (p7-p8)]; at 2-3 years of age, systematic behavioral tests (e.g., climbing, footprint analysis, and swimming) showed only minor differences between control (n = 5) and operated (n = 10) animals; and (2) cutting on p4-p6; at 1 month these opossums exhibited coordinated walking movements but were unabl ... | 1998 | 9412512 |
| bdnf is expressed at the crush site after spinal cord lesion in newborn opossum (monodelphis domestica). | brain-derived neurotrophic factor (bdnf) supports the regeneration of axotomized motoneurons in vitro. to study the role of bdnf in vivo, a partial cdna encoding the bdnf of the opossum (monodelphis domestica) was cloned by reverse transcription-polymerase chain reaction. the sequence was highly homologous to the bdnf of several mammals and chick. the spinal cord of newborn opossums was lesioned and allowed to regenerate in its entirety in a culture system for 3 days. in response to lesion, cell ... | 1997 | 9383223 |
| nitrergic modulation of cholinergic responses in the opossum lower oesophageal sphincter. | 1. electrical field stimulation (efs) of the superfused lower oesophageal sphincter from opossum (monodelphis domestica) elicited biphasic responses. the first phase (relaxation) was strictly dependent on the duration of the efs. the second phase (contraction) started following termination of the efs (< or = 15 hz). efs at frequencies above 15 hz led only to contraction, which started immediately upon initiation of the stimulation. 2. in the presence of ng-nitro-l-arginine (l-noarg; 0.1-300 micr ... | 1997 | 9401767 |
| features of the auditory development of the short-tailed brazilian opossum, monodelphis domestica: evoked responses, neonatal vocalizations and synapses in the inferior colliculus. | the onset of hearing in anesthetized south american opossums (monodelphis domestica) was determined by the measurement of evoked potentials to click stimuli from the vertex of the skull immediately over the inferior colliculus. evoked potentials were first recorded at postnatal day 24 at a threshold of 83 db spl; thresholds declined over subsequent weeks to below 58 db at 40 days. isolation calls emitted by the pups had stereotypic spectra with peaks at near 13 khz and an octave higher. such cal ... | 1997 | 9387986 |
| developmentally regulated markers in the postnatal cervical spinal cord of the opossum monodelphis domestica. | the aim of this study was to identify developmentally regulated immunocytochemical markers to assess development in the cervical spinal cord of monodelphis domestica. we demonstrate that two commercially available antibodies exhibit altered patterns of distribution during early postnatal development. although neurofilament staining was present at birth, only the phosphorylated form, recognised by monoclonal antibodies 2f11 or smi31 could be detected. non-phosphorylated neurofilament, recognised ... | 1997 | 9370059 |
| h-ras oncogene activation in invasive uvr-induced corneal sarcomas of the opossum monodelphis domestica. | chronic exposure to ultraviolet radiation (uvr) induces corneal sarcomas in the south american opossum monodelphis domestica. cell lines are readily established from these tumors. northern blotting of mrna from six such cell lines revealed high expression of the h-ras oncogene. h-ras cdna from an eye tumor cell line was cloned and characterized; the germline sequence of codons 12, 13, and 61 was confirmed by examination of h-ras sequences amplified from liver dna by the polymerase chain reaction ... | 1997 | 9364932 |
| aldolase c polymorphism in the laboratory opossum, monodelphis domestica. | a two-allele polymorphism in aldolase c was identified in brain extracts of grey short-tailed opposums, monodelphis domestica, by electrophoresis in starch or cellulose acetate gels. pedigree data were consistent with autosomal codominant inheritance. the polymorphism was present in two of the six genetically distinct laboratory populations that have been established for this species. | 1997 | 9363598 |
| development of olfactory marker protein and n-cam expression in chemosensory systems of the opossum, monodelphis domestica. | using olfactory marker protein (omp) and neural cell adhesion molecule (n-cam) immunohistochemistry, the present study describes development of olfactory and vomeronasal systems in pre- and postnatal opossums, monodelphis domestica. as revealed by omp expression, development of the main olfactory system precedes that of the vomeronasal system by 1-2 weeks. omp is expressed throughout (homogeneously) the nerve and glomerular layers of the main (mob) but is expressed more strongly (heterogeneously ... | 1997 | 9360317 |
| development of vomeronasal receptor neuron subclasses and establishment of topographic projections to the accessory olfactory bulb. | previous studies of the adult vomeronasal system have shown that vomeronasal receptor neurons in the middle layer (expressing gi alpha 2) and deep layers (expressing go alpha) of the sensory epithelium project to the anterior and posterior parts of the accessory olfactory bulb (aob), respectively. in the present study, the development of the two populations of vomeronasal receptor neurons and their segregated projections were investigated in the opossum, monodelphis domestica. antibodies to g pr ... | 1997 | 9352103 |
| myelination of the ventral and dorsal roots of the c8 and l4 segments of the spinal cord at different stages of development in the gray opossum, monodelphis domestica. | we have quantified the number and size of myelinated fibers of the ventral and dorsal roots of selected segments that innervate the forelimbs (c8) and hindlimbs (l4) in the developing opossum, monodelphis domestica. the gray opossum was chosen because it is born very immature and its somatomotor development occurs almost entirely postnatally. after aldehyde fixation, osmium postfixation, and resin embedding, the roots were cut transversely (1.5 pm), stained with toluidine blue, and observed and ... | 1997 | 9295147 |
| ultraviolet radiation a-induced precursors of cutaneous melanoma in monodelphis domestica. | two groups of 30 dorsally shaved opossums (monodelphis domestica) were exposed three times per week for 81 weeks to 250 j/m2 of uv radiation from fs40 sunlamps (approximately 150 j/m2 of uv radiation b; uv-b), or to 2.5 x 10(4) j/m2 of uv radiation a (uv-a) from filtered f40blb fluorescent lamps (black lights). animals were monitored for the appearance of nonmelanoma skin tumors (nmsts) and melanocytic hyperplasia (mh). after 81 weeks of exposures, the prevalence of nmsts was 71% and 4% for anim ... | 1997 | 9288772 |
| extreme bilateral molar rotation in monodelphis domestica (marsupialia: didelphidae). | rotation of a tooth around an axis perpendicular to the occlusal plane through angles approaching 180 degrees is a rare anomaly found in the mammalian dentition. a specimen of monodelphis domestica was found to show such extreme rotation of both lower last molars, with consequent disruption of normal occlusion and wear. a review of the literature discovered 41 other reported cases of extreme rotation, from four different orders of mammals. the distribution of extreme rotation within the dentitio ... | 1997 | 9347121 |
| s-100 immunoreactivity in melanomas of the south american opossum monodelphis domestica. | s-100 immunoreactivity was determined 1) in foci of melanocytic hyperplasia, 2) in naturally occurring, ultraviolet radiation-induced, and 9,10-dimethyl-1,2-benzanthracene (dmba)-induced primary melanomas, and 3) in metastatic melanoma lesions in the south american opossum monodelphis domestica. preneoplastic lesions of melanocytic hyperplasia contained scattered cells with s-100-positive nuclei. all primary melanomas, with the exception of a single dmba-induced tumor, contained cells with s-100 ... | 1997 | 9240844 |
| developmental anatomy of the primary olfactory pathway in the opossum monodelphis domestica. | it has been shown in previous studies that the marsupial central nervous system is born at a relatively immature state. although olfaction is thought to play a role in guiding the locomotion of the newborn, the cellular substrates on which this notion is based have not been systemically investigated. this review article summarises the anatomical development of the primary olfactory pathway in the postnatal monodelphis. the olfactory epithelium and bulb appear morphologically immature at birth al ... | 1997 | 9225163 |
| fate of allogeneic skin transplantations in a marsupial (monodelphis domestica). | previously we reported that the south american gray short-tailed opossum, monodelphis domestica, had an mhc class-i locus similar to that of eutherian species. in addition to the detection of lymphocyte antigens by cytotoxic antisera, we concluded that this marsupial rejected allogeneic skin grafts, as would be expected of animals with mhc class-i polymorphism. however, this conclusion was based on a limited number of skin transplants that were assayed for only a short period. here we report the ... | 1997 | 9241631 |
| ultrasonographic pregnancy detection and inhalation anesthesia in the gray short-tailed opossum (monodelphis domestica). | female gray short-tailed opossums (monodelphis domestica) with known breeding dates were anesthetized with isoflurane for ultrasonographic pregnancy detection. beginning on gestational day 9, gravid females could be identified using a 9-mhz mechanical sector-scanning transducer equipped with a standoff pad. fluid-filled vesicles 3 to 4 mm in diameter were seen within the thick-walled uteri on gestational days 9 and 10. visualization revealed loss of individual vesicles, with replacement by thick ... | 1997 | 9241630 |
| sex differences and the development of social behavior in a marsupial, the gray short-tailed opossum (monodelphis domestica). | the effects of sex and age on social behavior were examined in gray short-tailed opossums (monodelphis domestica), small didelphid marsupials. each animal received five behavior test batteries spanning prepubertal to postpubertal ages. each test battery consisted of two tests with animals of the same age, one with a male and one with a female. precopulatory behavior toward females, intermale fighting requiring test interruptions as well as scent marking behavior were seen at higher levels in mal ... | 1997 | 9177557 |
| development in vitro of marsupials: a comparative review of species and a timetable of cleavage and early blastocyst stages of development in monodelphis domestica. | the development of marsupial oocytes and embryos in vitro is reviewed. most stages of development have been cultured successfully, usually in a complex medium with added fetal calf serum. simpler media without added serum have been developed for fertilization and cleavage in vitro. culture systems have been established for oocyte maturation and fertilization in the grey short-tailed opossum and for cleavage from the zygote to the early expanding unilaminar blastocyst in a number of other marsupi ... | 1997 | 9184350 |
| cis-urocanic-acid-induced suppression of contact hypersensitivity in monodelphis domestica is prevented by ultraviolet a radiation/photoreactivating light. | the suppression of contact hypersensitivity by uvb (280-320 nm) radiation can be prevented by photoreactivating light (prl; 320-400 nm) in the opossum monodelphis domestica, implicating epidermal dna lesions as the immunosuppressive impairment. however, contact hypersensitivity can also be suppressed in the opossum with exogenous cis-urocanic acid, a molecule which is produced in uvb-irradiated epidermis and is a second potential mediator of photo-immunosuppression apparently independent of uvb- ... | 1997 | 9066512 |
| transthyretin distribution in the developing choroid plexus of the south american opossum (monodelphis domestica). | the distributions of transthyretin and albumin in the choroid plexus during brain development have been compared. the south american opossum was chosen because the young are born around the time of choroid plexus formation. previous work showed that in the adult opossum, transthyretin is expressed in the choroid plexus cells. however, systematic studies of transthyretin in the choroid plexus during development have not been carried out before. transthyretin was present in 90-95% of the choroidal ... | 1997 | 9027302 |
| spontaneous pathology of the gray short-tailed opossum (monodelphis domestica). | the gray short-tailed opossum, monodelphis domestica, is a newly established laboratory animal that is becoming increasingly important to biomedical research. because little disease information is available for this species, we reviewed records for spontaneous gross and histologic lesions and microbiologic results in 150 m. domestica necropsies during an 11-year period. we identified 150 (91 female, 59 male) animals from 441 necropsy cases which were controls in experimental protocols or were me ... | 1997 | 9051643 |
| the laboratory opossum (monodelphis domestica) in laboratory research. | | 1997 | 11528041 |
| autoradiographic localization of arginine vasopressin binding sites in the brain of adult and developing brazilian opossums. | we are utilizing the brazilian short-tailed opossum, monodelphis domestica, to study the development of the vasopressinergic system. earlier studies demonstrated that arginine vasopressin-like immunoreactivity was present very early in the brazilian opossum brain, suggesting a role for vasopressin in the developing central nervous system of mammals. in this study, we have utilized [3h]arginine vasopressin autoradiography to describe the distribution of arginine vasopressin binding sites in adult ... | 1997 | 9150896 |
| postnatal development and the differential expression of presynaptic terminal-associated proteins in the developing retina of the brazilian opossum, monodelphis domestica. | in the present study we have characterized the postnatal (pn) development of the retina in the brazilian opossum, monodelphis domestica. monodelphis, a small, pouchless marsupial, undergoes a protracted period of postnatal development. using bromodeoxyuridine immunohistochemistry, we have investigated postnatal neurogenesis of the retina. in addition, we have examined the differentiation of the retina by using antibodies directed against the presynaptic terminal-associated proteins synaptotagmin ... | 1996 | 8922678 |
| intersexual phenotypes and sex chromosome complements of five south american opossums (monodelphis domestica). | intersexual opossums (monodelphis domestica) from a large captive colony are described. these are the first naturally existing new world (didelphoid) intersexual marsupials for which reproductive phenotype and sex chromosome constitution are reported. one animal was xx, two were xy, and two were xo; all had lower body weight than normal males or females and the overall appearance of females. they were first recognized as abnormal by the presence of a small flaccid, nonstalked scrotum, markedly s ... | 1996 | 8905590 |
| development of spontaneous locomotor behaviors in the opossum, monodelphis domestica. | the development of spontaneous locomotor behaviors was studied in the opossum monodelphis domestica. the newborn opossum performs alternate, rhythmic movements with its forelimbs to crawl on the mother's belly where it attaches to a nipple, and its hindlimbs are little more than embryonic buds. the forelimbs retain the above movements for about 3 weeks, while the hindlimbs begin to move late in the second week. when detached from the nipple at 2-3 weeks, the pup can support its weight on the for ... | 1996 | 8905136 |
| testis development in the opossum monodelphis domestica. | testis development in the grey short-tailed opossum, monodelphis domestica, was investigated by light and electron microscopy in 180 animals. on the day of birth, half the karyotyped males were found to have histologically differentiated testes. by day (d) 1 testicular cords were clearly distinguished in all xy gonads and the tunica albuginea was fully developed. at this stage the large and pale primordial germ cells could be differentiated from dark pre-sertoli cells. from d 3 the testis became ... | 1996 | 8886961 |
| expression of myelin proteins in the opossum optic nerve: late appearance of inhibitors implicates an earlier non-myelin factor in preventing ganglion cell regeneration. | the pattern of appearance of myelin-associated proteins in the visual system of the brazilian opossum monodelphis domestica is described. whole mounts of optic nerve, chiasm, and optic tract were sectioned horizontally and incubated with antibodies to myelin basic protein (mbp), proteolipid protein (plp), myelin-associated glycoprotein (mag), "rip," and the neurite inhibitory protein (in-1), followed by visualization with diaminobenzidine and a peroxidase-conjugated secondary antibody. plp is fi ... | 1996 | 8841919 |
| the development of articular cartilage: ii. the spatial and temporal patterns of glycosaminoglycans and small leucine-rich proteoglycans. | articular cartilage is both morphologically and biochemically heterogeneous. its susceptibility to degenerative diseases such as arthritis and its limited repair capacity has made cartilage the focus of intense study; surprisingly, little is known of its development. using a panel of specific antibodies, we have documented the temporal and spatial patterns of the small leucine-rich proteoglycans fibomodulin, decorin and biglycan in the developing knee cartilage of the marsupial south american op ... | 1996 | 8771393 |
| the development of articular cartilage: i. the spatial and temporal patterns of collagen types. | articular cartilage is both morphologically and biochemically heterogeneous. its susceptibility to degenerative diseases such as arthritis and its limited repair capacity have made cartilage the focus of intense study; surprisingly, little is known of its development. using a panel of specific antibodies, we have documented the temporal and spatial patterns of collagen types i, ii, iii, vi and x in the developing knee cartilage of the marsupial monodelphis domestica from parturition to adulthood ... | 1996 | 8771392 |
| effect of chronic exposure to ultraviolet radiation and photoreactivation on life span and tumor development in the marsupial monodelphis domestica. | the effect of exposure to chronic ultraviolet (uv) radiation on life span was examined in monodelphis domestica, which is capable of photoreactivation repair of uv-radiation-induced pyrimidine dimers. shaved monodelphis were exposed to 500 j/m2 uv radiation, 500 j/m2 uv radiation then 90 min of photoreactivating light (prl), or 90 min of prl three times weekly for 104 weeks. opossums were weighed weekly; samples for serum chemistry and hematology testing were obtained periodically. complete post ... | 1996 | 8693068 |
| characterization of the brainstem auditory evoked potential (baep) in the grey short-tailed opossum (monodelphis domestica). | brainstem auditory evoked potentials (baep) have been measured and characterized in the marsupial monodelphis domestica in response to toneburst stimulation. five peaks are usually identified. the baep occurs within a time window of 5 ms starting 1.2 ms after onset of stimulation. latencies decrease with increasing stimulus level at a rate of about -11 microsecond/db. at high stimulus frequencies latencies are shorter than with lower frequencies and shorten at a rate of about -0.2 ms/octave. the ... | 2003 | 8879448 |
| the vestibular primary afferents and the vestibulospinal projections in the developing and adult opossum, monodelphis domestica. | the gray short-tailed opossum monodelphis domestica is born in a very immature state (eyes and ears closed, budlike hindlimbs, etc.) 14 days post-coitum, but it can locomote with its forelimbs from the mother's genital aperture to a nipple to which it attaches. the forelimb movements allowing this behavior may be the expression of central pattern generators in the spinal cord, but sensory clues must guide it. one such system may be the vestibular system, which senses linear and angular accelerat ... | 1996 | 8800425 |
| analysis of non-linear cochlear mechanics in the marsupial monodelphis domestica: ancestral and modern mammalian features. | the acoustic distortion product 2f1-f2 was measured in the ear canal of the gray short-tailed opossum. monodelphis domestica, during stimulation with two pure tone stimuli of the frequencies f1 and f2 (f1 < f2). from 2f1-2f growth functions for different primary frequencies from 4 to 85 khz, a distortion threshold curve was obtained describing the relative threshold of non-linear mechanical processes in the cochlea. distortion products could be measured over the entire investigated frequency ran ... | 1996 | 8789810 |
| vomeronasal system involvement in response to conspecific odors in adult male opossums, monodelphis domestica. | the present study was designed to test the hypothesis that preferential nuzzling of unfamiliar conspecific odors by male opossums is vomeronasally mediated. opossums were presented with vials containing their own odors (own) and vials with odors from unfamiliar conspecifics (novel) both before and after (expt. 1) or only after (expt. 2) vomeronasal nerve (vnnx) or sham (sham) surgery. nuzzling duration was greater for novel before (expt. 1) and after (expts. 1 and 2) surgery both in vnnx and sha ... | 1996 | 8762161 |
| characterization and ontogeny of synapse-associated proteins in the developing facial and hypoglossal motor nuclei of the brazilian opossum. | the characterization and ontogeny of synapse-associated proteins in the developing facial and hypoglossal motor nuclei were examined in the brazilian opossum (monodelphis domestica). immunohistochemical markers utilized in this study were the synaptic vesicle-associated proteins synaptophysin and synaptotagmin; a synaptic membrane protein, plasma membrane-associated protein of 25 kda (snap-25); a growth cone protein, growth-associated phosphoprotein-43 (gap-43); and the microtubule-associated pr ... | 1996 | 8725306 |
| a new dna marker, u15557, is linked to protease inhibitor and adenylate kinase-1 in the laboratory opossum, monodelphis domestica. | a 323-bp dna fragment (u15557) was isolated, cloned, and sequenced after polymerase chain reaction (pcr) amplification from monodelphis domestica genomic dna. a hindiii restriction fragment length polymorphism was identified in this species using the u15557 pcr, fragment as a hybridization probe. dna samples exhibited either a 6.4 kb band, a 7.2 kb band, or both bands simultaneously. behaviour of these two variants in family studies was consistent with codominant autosomal inheritance. linkage b ... | 1996 | 8856903 |
| the hormonal induction of mating behavior in female gray short-tailed opossums (monodelphis domestica). | the activating effects of estradiol alone and of estradiol plus progesterone on copulation and related behavior were examined in ovariectomized female gray short-tailed opossums. following receipt of subcutaneous estradiol (e) or cholesterol (c) implants, e-females showed less screeching threat behavior toward intact males than c-females. intact males showed more precopulatory behavior toward e- than toward c-females, and 20% of e-females and no c-females copulated with males. in a second experi ... | 1996 | 8724178 |
| vomeronasal organ removal blocks pheromonal induction of estrus in gray short-tailed opossums (monodelphis domestica). | estrus is induced in female gray short-tailed opossums (monodelphis domestica) by exposure to male chemical signals (pheromones). isolated females remain anestrous, but direct exposure to a male or his scent-marked cage induces estrus within 4-6 days. the objective of this study was to investigate the importance of the vomeronasal organ in detection of and response to estrus-inducing pheromones. the vomeronasal organ was surgically removed through the palate from 8 females (vnx); 5 females (sham ... | 1996 | 8788205 |
| central ph chemosensitivity in the newborn opossum monodelphis domestica. | | 1996 | 9030301 |
| egg maturation and fertilization in marsupials. | this brief review summarizes our knowledge of the morphological events that are associated with oocyte maturation and fertilization in marsupials in which it has been suggested that there are marked differences from eutherians in both the developmental timetable of oocyte maturation and in some of the processes associated with sperm-egg interaction. most of the data have been obtained from studies on four species: monodelphis domestica, sminthopsis crassicaudata, sminthopsis macroura, and tricho ... | 1996 | 8870085 |
| gamete biology of the new world marsupial, the grey short-tailed opossum, monodelphis domestica. | mammalian gametes undergo a series of functional and developmental changes that culminate in fertilization. in order to appreciate the necessity for such complex processes as sperm maturation, capacitation and the intimate sperm-egg interactions leading to gamete fusion, it is important to understand how gametes may have evolved. in this respect, marsupials are particularly relevant since they exhibit features reminiscent of both non-mammalian vertebrates and eutherian mammals. the grey short-ta ... | 1996 | 8870084 |
| a comparison of oocyte organelles in monodelphis domestica with those of other marsupials and eutherians. | this paper reviews the current knowledge of oocyte cytology in marsupials, particularly monodelphis domestica, and eutherian mammals. some of the conspicuous features will be described and their function discussed. despite many fundamental similarities between the oocytes of eutherian mammals and marsupials, some aspects are different (e.g. growth pattern, final size, timetable of cytoplasmic maturation and utilization of storage material during early cleavage stages), when most of the vesicles ... | 1996 | 8870077 |
| ontogeny of hearing in the marsupial, monodelphis domestica, as revealed by brainstem auditory evoked potentials. | auditory development was studied in the brazilian short-tailed opossum, monodelphis domestica, using the brainstem auditory evoked potential (baep). consistent responses can first be recorded 29 days after birth. the hearing range at the onset of hearing is limited to 5-20 khz with lowest thresholds of 60 db spl at 8-12 khz. during ontogeny, the hearing range expands towards lower and higher frequencies and thresholds decrease until the adult audiogram is obtained by about day 40. peak latencies ... | 1995 | 8647737 |
| myelin-associated neurite growth-inhibitory proteins and suppression of regeneration of immature mammalian spinal cord in culture. | neurite outgrowth across spinal cord lesions in vitro is rapid in preparations isolated from the neonatal opossum monodelphis domestica up to the age of 12 days. at this age oligodendrocytes, myelin, and astrocytes develop and regeneration ceases to occur. the role of myelin-associated neurite growth-inhibitory proteins, which increase in concentration at 10-13 days, was investigated in culture by applying the antibody in-1, which blocks their effects. in the presence of in-1, 22 out of 39 prepa ... | 1995 | 7479918 |
| hearing in the marsupial monodelphis domestica as determined by auditory-evoked brainstem responses. | the audiogram of the marsupial monodelphis domestica was determined by measuring brainstem auditory-evoked potentials in response to pure-tone stimuli of 2-90 khz. the frequency range at 60 db spl comprises frequencies between about 2.3 and 63 khz. the best frequency range with average thresholds of 3 db spl in young adults (3 months old) is between 12 and 16 khz. in older animals, thresholds are higher. the overall shape and frequency range of the audiogram and the absolute thresholds indicate ... | 2006 | 8833313 |
| migrating luteinizing hormone-releasing hormone (lhrh) neurons and processes are associated with a substrate that expresses s100. | luteinizing hormone-releasing hormone (lhrh) containing neurons arise in the region of the medial olfactory placode and migrate into the developing olfactory bulbs and basal forebrain along branches of the terminal and vomeronasal nerves. the neurons ultimately come to reside in olfactory and septo-preoptic areas and project extensively to several brain regions, including the preoptic area and median eminence. the present study examined the expression of a glial-associated guidance molecule, s10 ... | 1995 | 8665661 |
| the effects of neonatal treatment with tamoxifen on sexually dimorphic behavior and morphology in gray short-tailed opossums (monodelphis domestica). | the effects of postnatal exposure to the antiestrogen tamoxifen on sexually dimorphic behavior and morphology in adult male and female gray short-tailed opossums were examined. following gonadecomy and treatment with estradiol in adulthood, neonatally tamoxifen-treated (tx) females showed less female-typical screeching threat behavior and tx males showed less male-typical precopulatory behavior than same-sex controls. while testes failed to descend and phalluses were shorter in juvenile tx males ... | 1995 | 7490006 |
| lectin histochemical identification of carbohydrate moieties in opossum chemosensory systems during development, with special emphasis on vva-identified subdivisions in the accessory olfactory bulb. | lectins, sugar-binding molecules of nonimmune origin, were used in this study to describe the development of the main olfactory and vomeronasal systems in the brazilian gray short-tailed opossum, monodelphis domestica. a battery of seven lectins of the n-acetylgalactosamine/galactose-binding group was used. of the seven lectins, only two, vicia villosa agglutinin (vva) and griffonia (bandeiraea) simplicifolia lectin i-isolectin b4 (gs i-b4), were specific to the vomeronasal system. the other fiv ... | 1995 | 7595957 |
| ontogeny of the skin and the transition from scar-free to scarring phenotype during wound healing in the pouch young of a marsupial, monodelphis domestica. | the marsupial monodelphis domestica provides a versatile model for the study of "fetal" wound healing. the pouch young of this species have been used to perform a systematic histological study of wound healing and skin development throughout pouch life; from pouch day 0 to pouch day 30 with comparisons drawn against adults. we have demonstrated that pouch young heal without macroscopic scars if wounded before pouch day 9 and that a transition into a scarring healing phenotype occurs around the n ... | 1995 | 7750642 |
| neuron-specific enolase as a marker of hypothalamo-neurohypophyseal development in postnatal monodelphis domestica (marsupialia). | in the newborn monodelphis domestica, pituitary and brain are far from their definite shape and structural organization. the presumptive neurohypophysis appears as a mass of proliferating cell immunonegative for neuron-specific enolase (nse) in the newborn, while perikarya positive for nse are present in the rostroventral area of the hypothalamus. at the same time, the periventricular areas of the brain, consisting of proliferating cells, are non-reactive for nse. in the 2.5-day-old specimens of ... | 1995 | 7603626 |
| sperm pairing in the opossum increases the efficiency of sperm movement in a viscous environment. | in order to understand why sperm pairing has evolved in most american marsupials, the movement parameters of spermatozoa from monodelphis domestica were analyzed after incubation in capacitating medium for 15 min, 2 h, and 24 h to induce a proportion of sperm pairs to uncouple. motility characteristics of paired and single spermatozoa were measured in media of differing composition and viscosity by means of computer-aided semen analysis. in minimum essential medium or in rpmi 1640 medium alone, ... | 1995 | 7780016 |
| ultraviolet radiation-induced skin lesions in laboratory opossums (monodelphis domestica) exposed from the weanling stage. | after repeated exposure to ultraviolet radiation, adult laboratory opossums (monodelphis domestica) may develop hyperplasia and neoplasia of the shaved skin. we exposed opossums from the weanling stage (8-10 weeks after birth) and compared the incidence of lesions at designated time points with those observed following introduction of adults (around 5 months old) to the same irradiation protocol (125 j/m2 of uvb three times each week for up to 40 weeks). the overall incidence of hyperplasia and ... | 1995 | 7598539 |
| congestive heart failure in a marsupial (monodelphis domestica). | | 1994 | 7898039 |
| respiratory rhythm in the isolated central nervous system of newborn opossum. | 1. respiratory activity was recorded from spinal ventral roots in the isolated intact central nervous system (cns) of newborn opossum, monodelphis domestica. these signals occurred in synchrony with movements of the ribs and the electromyogram (emg) recorded from the intercostal muscles during inspiration. rhythmical activity could be recorded for more than 6 h in acute preparations. 2. the rhythm-generating region was shown to be located in the lower brain stem by perfusing different cns region ... | 1994 | 7852902 |
| a new hindiii rflp of nras in the laboratory opossum, monodelphis domestica. | | 1994 | 7695130 |
| malignant melanoma in ultraviolet irradiated laboratory opossums: initiation in suckling young, metastasis in adults, and xenograft behavior in nude mice. | litters of suckling young of the laboratory opossum (monodelphis domestica) were irradiated with uv light from sunlamps with a spectral emission peak at 302 nm (uvb) to induce melanocytic nevi. total doses of 0.87-5.0 kj/m2 were divided equally among up to 14 exposures during the 19 days from birth. of 358 sucklings exposed, 217 survived to weaning, and 22 (10%) possessed a nevus when shaved and examined at or after weaning. affected animals were then exposed 3 times/week to 125 j/m2 of uvb for ... | 1994 | 7954432 |
| development of craniofacial musculature in monodelphis domestica (marsupialia, didelphidae). | development of craniofacial muscles of monodelphis domestica (marsupialia, didelphidae) is described. in a period of 4-6 days all craniofacial muscles in m. domestica progress from myoblast condensation, to striated myofibers that are aligned in the direction of adult muscles and possess multiple, lateral nuclei. this process begins 1 to 2 days before birth and continues during the first few days after birth. compared to other aspects of cranial development, muscle development in m. domestica is ... | 1994 | 7799438 |
| [the topography of the pancreas of monodelphis domestica (marsupialia)]. | shape and position of the pancreas of monodelphis domestica are described in situ after fixation of the animals with bouin's fluid. the right lobe of the pancreas is the smallest of the three organ parts. the body of the pancreas is placed in a transverse position in the cranial area of the peritoneal cavity. ventral access to it is relatively difficult due to the position of the greater parts of the body dorsal to the stomach. in contrast, the left lobe reaches far caudad. typical for monodelph ... | 1994 | 7956809 |
| microtubule configurations in oocytes, zygotes, and early embryos of a marsupial, monodelphis domestica. | the marsupials represent a separate evolutionary lineage from eutherians from which they diverged over 100 million years ago. in order to explore the origin and mode of centrosome inheritance amongst this group of mammals, this study investigates the microtubule organization during fertilization, parthenogenesis, and polyspermy in the didelphid, monodelphis domestica. microtubules and dna were visualized in maturing ovarian oocytes, parthenogenetically activated oocytes, monospermic and polysper ... | 1994 | 8026625 |
| developmental distribution of gfap and vimentin in the brazilian opossum brain. | cells of glial origin are involved in the morphogenesis of the mammalian central nervous system (cns). characterization of glial-associated proteins during neurogenesis and differentiation may aid in understanding the complexity of cns development. we have utilized immunoblotting and immunohistochemistry to characterize the developmental profiles of glial fibrillary acidic protein (gfap) and vimentin (vim) in the brain of the brazilian opossum, monodelphis domestica. typical of marsupials, cns m ... | 1994 | 8077462 |
| cellular aspects of the development of diarthrodial joints and articular cartilage. | there have been many reports on the histological development of mammalian diarthrodial or synovial joints. while these are useful for comparative purposes, they tell us little of the cellular basis of joint morphogenesis which must underlie a number of morphogenetic defects. the process of joint morphogenesis is complex and can be subdivided into a number of facets and this report will focus on 2 of them. first, the process of joint cavitation in the chick metatarsophalangeal joint, where we pro ... | 1994 | 7928634 |
| spontaneous pituitary adenomas in the brazilian gray short-tailed opossum (monodelphis domestica). | | 1994 | 8053134 |
| characterization of cdna encoding basic fibroblast growth factor of the marsupial monodelphis domestica. | we have isolated and characterized a 1,593-bp cdna containing the coding region of the basic fibroblast growth factor (bfgf) gene of a marsupial, the opossum monodelphis domestica. the encoded protein is 156 amino acids long. the bfgf gene of m. domestica is 82-87% identical to the bfgf genes of placental mammals at the nucleotide level and 92-93% identical to these genes at the level of the amino acids encoded. regions of the bfgf molecule important in heparin binding, high-affinity receptor bi ... | 1994 | 8024698 |
| development of spinal cord in the isolated cns of a neonatal mammal (the opossum monodelphis domestica) maintained in longterm culture. | the cns of the newly born opossum removed in its entirety survives and maintains its electrical excitability in suitable culture media for up to ten days at 25 degrees c. the structure of the developing neonatal spinal cord has been studied in the intact animal and in the cultured cns. the differentiation and survival of individual cells and subcellular structures were followed at the light and electron microscopic level. the expression of cell markers in neuronal and glial cells was studied imm ... | 1994 | 8006676 |
| the development of serotonergic projections to the olfactory bulb of monodelphis domestica (the grey, short-tailed opossum). | the offspring of monodelphis domestica (grey, short-tailed opossum) are born in a very immature state after a short (14-day) gestation period. as a result, they provide a useful mammalian model for examining quite early stages of brain maturation. the present study demonstrates that the onset and development of serotonergic (5-ht) projections to the monodelphis olfactory bulb can be traced entirely after birth. 5-ht was visualized in tissue sections from postnatal day 5 (p5), p10, p20, p30, and ... | 1994 | 8174233 |
| blood collection and surgical procedures for the laboratory opossum (monodelphis domestica). | procedures have been developed for collecting blood samples from the laboratory opossum (monodelphis domestica) and for conducting survival surgery on adults. blood samples up to 1 ml were collected routinely by cardiac puncture of animals anesthetized by inhalation of methoxyflurane or halothane with minimal risk; however, halothane required more careful monitoring. surgical procedures such as partial hepatectomy unilateral hysterectomy, and tail wound repair were safely accomplished on animals ... | 1994 | 8007664 |
| susceptibility to ultraviolet-induced corneal sarcomas is highly heritable in a laboratory opossum model. | the laboratory opossum, monodelphis domestica, develops hyperplasia and neoplasia of the corneal stroma after repeated exposure to low doses of ultraviolet radiation (uvr) (non-erythemic in skin). we exposed adult animals from genetically diverse families within our colony to determine whether there are any heritable components to the risk of this form of eye cancer. from about 5 months of age, animals were exposed 3 times a week to a dose of about 125 j/m2 of uvb (spectral peak = 302 nm). thirt ... | 1994 | 8262667 |
| placentation in the dasyurid marsupial, sminthopsis crassicaudata, the fat-tailed dunnart, and notes on placentation of the didelphid, monodelphis domestica. | a light microscope study of the choriovitelline (yolk sac) placenta of the dasyurid marsupial, sminthopsis crassicaudata, and some comparative observations on that of the didelphid, monodelphis domestica, were performed. in the former species, the placenta was composed of an invasive bilaminar, avascular, yolk sac and a non-invasive trilaminar, vascular yolk sac. the bilaminar yolk sac placenta had trophoblast giant cells that eroded the maternal epithelium, but there was no evidence of invasion ... | 1994 | 8182576 |
| the development of sensorimotor reflexes in the brazilian opossum monodelphis domestica. | the development of a number of sensorimotor reflexes was studied in the brazilian opossum monodelphis domestica. at birth, an opossum's forelimbs execute rhythmic, alternate movements which resemble swimming, whereas the hindlimbs are little more than embryonic buds that do not move independent of the trunk. it is possible, therefore, to witness the entire development of hindlimb motility, the advent of coordination between forelimbs and hindlimbs, and the development of ambulation. the followin ... | 1994 | 8038987 |
| differential omp expression in opossum accessory olfactory bulb. | using immunohistochemical techniques, olfactory marker protein (omp) was localized to the main (mob) and accessory (aob) olfactory bulbs of 30- and 45-day-old, and adult brazilian opossums, monodelphis domestica. entire olfactory nerve and glomerular layers of the adult opossum mob were darkly stained. in the adult aob the rostral half of these two layers was stained more intensely than the caudal half, and both parts were less darkly stained than the mob. this differential aob staining was not ... | 1993 | 8298073 |
| cell lines derived from ultraviolet radiation-induced benign melanocytic nevi in monodelphis domestica exhibit cytogenetic aneuploidy. | the gray short-tailed opossum, monodelphis domestica, develops dermal melanocytic nevi (mn) after long-term chronic exposure to uvb (midwavelength ultraviolet radiation) alone. we developed cell lines from six uvb-induced dermal benign melanocytic lesion biopsies. one of the mn was determined histologically to be a benign melanoma (bm), whereas the remainder were benign melanocytic hyperplasias (mh). the cell lines were not tumorigenic when injected subcutaneously into athymic nude mice. protein ... | 1993 | 8275453 |
| different rates of axonal degeneration in the crossed and uncrossed retinofugal pathways of monodelphis domestica. | the uncrossed retinofugal fibres in the marsupial monodelphis domestica form a separate bundle as they pass through the optic chiasm. the uncrossed fibres segregate from the crossed fibres a short distance before they reach the chiasm, gathering as an essentially exclusive bundle in the ventral part of the optic nerve. this bundle then passes laterally through the optic chiasm and into the optic tract. the distinctive position of the uncrossed fibres has allowed us to recognise that, surprisingl ... | 1993 | 8270955 |
| sex differences and the role of aromatization in the control of sexually dimorphic behavior and morphology in gray short-tailed opossums (monodelphis domestica). | sex differences in the activating effects of an aromatizable (testosterone, t) and a nonaromatizable (dihydrotestosterone, dht) androgen on sexually dimorphic scent marking and aggressive behavior were examined in gonadectomized gray short-tailed opossums. when compared with males, females showed less chest, head, flank, and hip marking and more fighting behavior in tests with stimulus females and threat behavior in tests with stimulus males following receipt of subcutaneous t, dht, or blank (b) ... | 1993 | 8225259 |
| neural aromatase activity in a marsupial, the gray short-tailed opossum (monodelphis domestica): ontogeny during postnatal development and androgen regulation in adulthood. | neural aromatase activity (aa) was measured in gray short-tailed opossums (monodelphis domestica) on the day of birth and at selected ages through adulthood. in adulthood, regulation by testicular androgens was examined. in mixed-sex samples of whole brain, aa was present at birth and increased until postnatal day (pd) 16. in hypothalamus-preoptic area (hpoa), significantly higher levels of aa were seen in animals on pd 16 than on pd 30 and pd 30 animals had higher levels of aa than all older ag ... | 1993 | 8403383 |
| developmental profile of galanin binding sites in the mammalian brain. | galanin (gal) is a 29-amino acid peptide widely distributed in the mammalian nervous system. recently, gal expression has been shown to increase during periods of neuronal degeneration (e.g., alzheimer's disease) and neuronal injury. our laboratory has previously reported that gal immunoreactivity (gal-ir) is robustly expressed during a time of cns plasticity, development. the striking gal-ir seen during times of cns morphogenesis and neurogenesis led us to the hypothesis that gal may play a rol ... | 1993 | 19912942 |
| lectin histochemical study of early postnatal vascularization of the developing pars distalis adenohypophysis of the gray short-tailed opossum (monodelphis domestica, marsupialia). | individuals from 18 litters between 0.5 day and 13 days post partum, and two adult specimens of monodelphis domestica (marsupialia), were studied by tem and lectin histochemistry. positive reactions for po-lectins in the developing pituitary were found in the vascular and/or perivascular elements; secretory cells did not react. positive vascular reactions varied with both the type of lectin and the age of the developing animal. in the adults, the reactions were reversed: there were no vascular, ... | 1993 | 8363038 |
| gonadal development in the opossum, monodelphis domestica: the rete ovarii does not contribute to the steroidogenic tissues. | the gonads of 273 animals, ranging in age from newborn to adult, were examined in serial histological sections. primordial germ cells were located in the hindgut, dorsal mesentery and gonadal primordia of neonates but were alkaline phosphatase negative. the testis differentiated between d 13 of gestation and birth, about half a day later. testis cords, composed of pre-sertoli cells and containing germ cells, were distributed peripherally in the gonad. ovarian differentiation began on d 6, when a ... | 1993 | 8270475 |
| effects of postnatal exposure to alcohol on reproductive physiology and sexually dimorphic behavior in a marsupial, the gray short-tailed opossum (monodelphis domestica). | the effects of postnatal exposure to alcohol on reproductive physiology and sexually dimorphic behavior and anatomy in adult male and female gray short-tailed opossums were examined. female responsiveness to male pheromones and fertility in both sexes were essentially normal in postnatally alcohol-treated animals. however, aspects of sexually dimorphic behavior were masculinized and defeminized in females and demasculinized in males following gonadectomy in adulthood and treatment with male (tes ... | 1993 | 8214429 |
| differential down-regulation of estrogen receptor-like immunoreactivity by estradiol in the female brazilian opossum brain. | the effects of estrus and prolonged estradiol benzoate (eb) treatment on estrogen receptor-like immunoreactivity (er-li) were studied in the female brazilian opossum (monodelphis domestica) brain. in general, both estrus animals and eb treated animals had reduced er-li in specific brain regions when compared to ovariectomized controls. these results support a down-regulatory role for estrogen in relation to its receptor in the brain, and indicate that er-li is differentially regulated in the mon ... | 1993 | 8374740 |
| novel articular cartilage structure in the south american opossum, monodelphis domestica. | articular cartilage provides smooth surfaces for low-friction, unrestricted movement of opposing skeletal elements. the surface topography of articular cartilage has been the subject of numerous studies and, with few exceptions, is considered to be smooth (at least at the light microscopic level). some studies have reported 'humps' on the articular surface which have been related to underlying chondrocytes residing very close to the surface. here we report on a highly nodular form of articular c ... | 1993 | 8226287 |
| nuzzling in the gray short-tailed opossum. ii: familiarity and individual recognition. | nuzzling is a chemosensory exploratory behavior that enables south american gray short-tailed opossums to dissolved dry conspecific odor deposits in naso-oral secretions and incorporate them into their vomeronasal organs. this report documents that male opossums nuzzle novel (unfamiliar conspecific) male odors significantly longer than familiar (own of familiar conspecific) male odors or clean substrates. such findings suggest that an important ethological function of nuzzling behavior involves ... | 1993 | 8511214 |
| nuzzling in the gray short-tailed opossum. i: delivery of odors to vomeronasal organ. | nuzzling in the gray short-tailed opossum (monodelphis domestica) is exhibited in response to conspecific odor deposits and is involved in chemosensory recognition. nuzzling consists of bouts of repeated forward rubbing motions (with intermittent tapping) with the ventral aspect of the snout over the odor source, while moistening it with naso-oral secretions. the role of nuzzling in odorant d delivery to the vomeronasal organ (vno) was investigated. five opossums were allowed to nuzzle conspecif ... | 1993 | 8511213 |
| ultraviolet radiation-induced corneal tumours in the south american opossum, monodelphis domestica. | chronic exposure of the south american opossum, monodelphis domestica, to ultraviolet radiation (uvr) induced 154 primary tumours of the cornea in 152 eyes. tumours developed gradually; frank neoplasia was preceded by non-neoplastic proliferation of corneal stromal fibroblasts (keratocytes) and extensive neovascularization. histologically, the majority of tumours (134 of 154) appeared to be fibrosarcomas arising from keratocytes, but about 12 per cent of the tumours (18 of 154) had a highly vasc ... | 1993 | 8366202 |
| in vitro fertilization and embryo culture in the grey short-tailed opossum, monodelphis domestica. | in vitro fertilization and early embryo culture was undertaken in the south american marsupial, the grey short-tailed opossum, monodelphis domestica. adult females were induced into oestrus by a system of pairing with an unfamiliar male and mature oocytes were recovered from the ovary 15-18 h after mating and placed in pre-warmed modified mem medium at 33 degrees c (basal body temperature) or 37 degrees c. spermatozoa recovered from the cauda epididymides of adult males were preincubated in medi ... | 1993 | 8345471 |
| cochlear place-frequency map in the marsupial monodelphis domestica. | in order to determine the place-frequency map of the cochlea in the marsupial monodelphis domestica, iontophoretic hrp-injections were made at several locations in the ventral cochlear nucleus. prior to iontophoresis the auditory neurons at these locations were characterized electrophysiologically. the resulting distribution of retrogradely labeled cochlear spiral ganglion cells was analysed by means of a three dimensional reconstruction of the cochlea. the map was established for frequencies be ... | 1993 | 8340271 |
| blood groups in a marsupial (monodelphis domestica). | we produced alloimmune sera against erythrocytes of the marsupial, monodelphis domestica. by absorption fractionation, six operationally monospecific blood typing reagents (hemolysins) were prepared. using segregation analyses, we found that each reagent detects a blood group antigen controlled by an autosomal dominant gene. with the description of these genetic markers, the utility of m. domestica as an animal model is enhanced. | 2007 | 8228172 |
| the development of the long descending propriospinal projections in the opossum, monodelphis domestica. | the origin of the long descending propriospinal (ldp) projections have been studied in adult and developing opossums, monodelphis domestica. this species has been chosen because of the considerable immaturity of the hindlimbs at birth, the postnatal appearance of their motility and the late development of coordination between them and the forelimbs. neuroanatomical tracing has indicated that some ldp projections form postnatally. the ones present at birth arise from the regions of the cord where ... | 1993 | 7683578 |