Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| postnatal changes in blood respiratory characteristics in an american opossum (didelphis virginiana). | the oxygen affinity of opossum blood changes in the postnatal period. the youngest opossums studied were 53 days of age (dated from the day of transit from vagina to pouch) and still confined to the maternal pouch: they had a blood p50 of 32.6 +/- 2.9 mm hg. the blood p50 value then increased significantly, in two steps. first, while the young were still in the pouch, blood p50 rose secondary to a rise in the concentration of 2,3-diphosphoglycerate (dpg). blood p50 and dpg concentration then rem ... | 1999 | 15307 |
| respiratory characteristics of opossum (didelphis virginiana) blood during chronic anemia. | in five adult opossums (didelphis virginiana), blood hemoglobin concentration was lowered from 12.3g% to 6.4g% by daily bleeding. blood p50 rose significantly (p is less than 0.05) from 44.5 mm hg to 47.4 mm hg and the concentration of 2, 3-diphosphoglycerate (dpg) increased from 14.17 mumol/g hb to 20.90 mumol/g hb. the observed shift in blood oxygen affinity was of similar magnitude to that recorded in humans with a similar degree of anemia, but the concomitant rise in dpg concentration was gr ... | 1978 | 26945 |
| response to cryptorchidism of the testis and epididymis of the opossum (didelphis virginiana). | adult male opossums, didelphis virginiana, were rendered hemicryptorchid for 35 days. the cyrptorchid testis exhibited a significant reduction in weight, while the contralateral testis had a compensatory weight gain compared with testes of untreated animals. histological changes in the cryptorchid testis included fibrosis of the tunica propria, involution of the seminiferous tubules and an apparent increase in the interstitial tissue. many seminiferous tubules were empty and germinal cells were ... | 1979 | 41944 |
| the vestibular complex of the american opossum didelphis virginiana. ii. afferent and efferent connections. | we have demonstrated the connectivity of the opossum's vestibular nuclei using degeneration, autoradiographic and horseradish peroxidase techniques and have found it to be generally comparable to that reported for the cat. apart from the primary input described in part i of our study, the cerebellum provides the major source of afferent connections to the vestibular complex. axons from the cerebellar cortex distribute mainly to vestibular areas which receive no primary afferent projections, e.g. ... | 1977 | 65367 |
| evidence for direct bulbospinal projections to laminae ix, x and the intermediolateral cell column. studies using axonal transport techniques in the north american opossum. | 1979 | 88996 | |
| experimental transmission of sarcocystis from icterid birds to sparrows and canaries by sporocysts from the opossum. | cowbirds (molothrus ater) and grackles (cassidix mexicanus) infected with muscle cysts of sarcocystis were fed to opposums (didelphis virginiana) and fecal sporocysts from the latter were given to sparrows (passer domesticus, family ploceidae), canaries (serinus canarius, family fringillidae) and ducks (anas platyrhynchos, family anatidae). asexual parasites were found in the endothelium of sparrows and canaries but not in ducks. when birds were kept 10 weeks or more after infection, muscle cyst ... | 1978 | 98622 |
| the electrocardiogram of the virginia opossum (didelphis virginiana). | 1998 | 106584 | |
| biosynthesis and secretion of testosterone by adrenal tissue from the north american opossum, didelphis virginiana, and the effects of tropic hormone stimulation. | 1975 | 173619 | |
| pulmonary reflexes and breathing pattern during sleep in the opossum. | paradoxical sleep (ps) in the opossum (didelphis virginiana) and other mammals is typically accompanied by irregular breathing, while even breathing is usually found during slow wave sleep (sws). during ps certain brainstem reflexes are depressed, and it is possible that similar depression of pulmonary reflexes could contribute to the observed ventilatory uneveness. to test this possibility, we assessed pulmonary reflexes in the opossum during sws and during ps when breathing was irregular. prol ... | 1990 | 184508 |
| tissue differentiation and susceptibility to embryonal tumor induction by ethylnitrosourea in the opossum. | opossums (didelphis virginiana kerr) exposed to 100 mg enu/kg in single or incremental doses early in postnatal life developed a spectrum of epithelial and mesenchymal neoplasms including several types of embryonal neoplasms not previously induced in laboratory animals. a correlation was apparent to a varying degree between susceptibility to tumor induction and the state of morphologic maturation of the presumed target tissues at the light microscopic level for embryonal tumors of the eye, kidne ... | 1979 | 225667 |
| spectrophotometric measurement of hemoglobin oxygen saturation in the opossum didelphis virginiana. | 1975 | 234330 | |
| prostaglandins and myogenic control of tension in lower esophageal sphincter in vitro. | active tension is produced by the lower esophageal sphincter (les) of north american opossum in vitro by a myogenic mechanism. strips of les, but not those from the esophageal body, contracted to prostaglandin (pg)f2 alpha, stable expoxymethano derivatives of pgh2 and to thromboxane b2. stable endoperoxides were more than 500 times more potent than pgf2 alpha. pgi2 and 6-keto pgf1 alpha were weak relaxants of les strips. les strips transformed arachidonic acid into contractile substances. this t ... | 1979 | 379920 |
| the opossum (didelphis virginiana) as a host for sarcocystis debonei from cowbirds (molothrus ater) and grackles (cassidix mexicanus, quiscalus quiscula). | sarcocystis-infected muscles from ducks, cowbirds, and grackles were fed to cats, opossums, rats, and a dog. only the opossum (didelphis virginiana) was a suitable definitive host. all opossums that were fed sarcocystis-infected cowbirds (molothrus ater) and grackles (cassidix mexicanus and quiscalus quiscula) passed sporocysts in their feces. opossums that ate the cowbirds had prepatent periods of 5 and 10 days and remained patent for at least 105 days. opossums that ate the grackles became pat ... | 1978 | 417165 |
| pairing of spermatozoa in the epididymis of the opossum (didelphis virginiana): a scanning electron microscopic study. | spermatozoa of the opossum, didelphis virginiana, were taken from three different regions of the epididymis and examined by scanning electron microscopy, phase-contrast and dark-field microscopy. it has been demonstrated that marked morphological changes occur in spermatozoa during their passage through the epididymis. in the first segment or head of the epididymis, spermatozoa are non-motile and the long axis of their nuclei is perpendicular to that of the tail. the nucleus is v-shaped with a t ... | 1979 | 464751 |
| structure of the esophagus in the adult opossum, didelphis virginiana. | the structure of the esophagus has been studied in the adult opossum, didelphis virginiana. a thickening of both layers of the muscularis externa occurs at the origin of the esophagus and may represent the upper esophageal sphincter; a massive expansion of the muscularis mucosae occurs in the region of the lower esophageal sphincter. the distribution of striated, mixed and smooth muscle in the muscularis externa differs in the inner and outer layers and elements of the myenteric plexus are found ... | 1979 | 474990 |
| the development of monoaminergic brainstem-spinal systems in the north american opossum. | evidence is presented for an early appearance of monoaminergic neurites within the spinal cord of the developing opossum. they are present within the marginal zone before hindlimb movements begin (stage i) and they start to grow into the intermediate zone by the time hindlimb movements are first observed (stage ii). monoaminergic neurites grow first into the dorsolateral intermediate zone and the intermediolateral cell column where they can be found by the beginning of stage ii. shortly thereaft ... | 1979 | 475000 |
| spinal projections from the mesencephalic and pontine reticular formation in the north american opossum: a study using axonal transport techniques. | the results from several experimental approaches lead to the following conclusions. the nucleus cuneiformis projects to at least lumbar levels of the spinal cord. its axons course through the ipsilateral sulcomarginal and ventral funiculi to distribute within lamina viii and adjacent portions of lamina vii. neurons within the nucleus reticularis pontis (rp), particularly within more medial parts of the nucleus, project through comparable routes to the same laminae. in addition, however, neurons ... | 1979 | 489785 |
| morphological observations on the mesonephros in the postnatal opossum, didelphis virginiana. | the mesonephros of the opossum persists for 3-4 weeks into the postnatal period. based on our observations of its structure, and the vital dye experiments of others, it appears that the opossum mesonephros is functional during the first 10 days of the postnatal period. the mesonephros of the newborn opossum consists of 35-45 nephron units which are structurally very similar to metanephric nephrons except that they lack a loop of henle. by the end of the first postnatal week, regression which pro ... | 1996 | 500493 |
| morphological observations on the metanephros in the postnatal opossum, didelphis virginiana. | the metanephros of the newborn opossum is very immature, consisting only of collecting tubules and a few immature nephrons. development during the postnatal period can be divided into two distinct phases. the initial phase occurs during the first 60 days of postnatal life and is concerned with nephronogenesis and the differentiation of nephrons that have formed during this period. the second phase lasts through the remainder of the postnatal period and is concerned with further differentiation a ... | 1979 | 541236 |
| general observations on the growth and development of the young pouch opossum, didelphis virginiana. | a 3-year study of general growth and development revealed a uniform increase in body length of young pouch opossums during the first 10 weeks of life. throughout this period, growth was linear and constant for all animals regardless of sex, litter size, or whether animals were obtained from first, second or third litters. body weights were somewhat more variable, but there were no significant sex differences. various aspects of external gross morphology are presented and discussed as they relate ... | 1978 | 567497 |
| development of the external muscle coats in the digestive tract of the opossum, didelphis virginiana. | development of the external musculature of the gastrointestinal tract has been studied in the stomach, small intestine and colon of the postnatal opossum. the muscle support is thin and poorly developed at birth, especially in the stomach and small intestine where only the inner layer is completely formed. the outer layer is discontinuous and formed by scattered myoblasts. the muscularis externa of the colon at birth is considerably thicker and both layers are present. subsequent development of ... | 1978 | 567924 |
| dipetalonema (acanthocheilonema) didelphis sp. n. (nematoda: filarioidea) from opossums, with a redescription of d. (a.) pricei (vaz and pereira 1934). | dipetalonema (acanthocheilonema) didelphis sp. n. recovered from the subcutaneous and periesophageal connective tissues of didelphis virginiana from several localities in the united states and of d. marsupialis from colombia is described. dipetalonema didelphis sp. n. resembles d reconditum and d. mansonbahri in size, in lacking a two-segmented buccal capsule, and in the female having a long, digitiform tail. dipetalonema reconditum, however, has a much longer glandular esophagus and d. mansonba ... | 1979 | 575550 |
| the organization of reticulo-olivo-cerebellar circuits in the north american opossum. | by employing the autoradiographic method we have determined that the inferior olivary nucleus receives input from the reticular formation of the midbrain, pons and, probably, the medulla. the remarkable thing about such connections is that they are not diffuse, but targeted in large part on restricted portions of the caudal acessory nuclei. from our previous studies it is clear that some of the olivary regions receiving reticular input also receive projections from the cerebral cortex, the spina ... | 1977 | 589453 |
| ventilatory effects accompanying spontaneous movement in the suckling opossum. | to determine whether spontaneous movement was associated with an organized respiratory response during early stages of mammalian development, we studied immature suckling opossums (didelphis virginiana) between 30 and 60 days of age. rate and depth of breathing were measured using pressure plethysmography and movement was assessed using electromyography of neck muscles. during air-breathing as well as during ventilatory chemostimulation with hypoxic, hypercapnic, and asphyxiant test gases, the o ... | 1977 | 597380 |
| an electron microscopic study of rubrospinal projections to the lumbar spinal cord of the opossum. | the rubrospinal system is a major suprasegmental input to the important interneuronal pool at the base of the lumbar dorsal horn in the north american opossum. after appropriate lesions, rubral axons and their synaptic terminals were found in electron micrographs of lamina iv, v and vi as well as within the dorsal extreme of lamina vii. degenerating terminals contact small diameter dendrites in the lateral terminal zone and large dendritic profiles in the medial terminal zone. correlating these ... | 1978 | 630404 |
| postnatal development of the epidermis in a marsupial, didelphis virginiana. | at birth the epidermis of the opossum is 43 micron thick and consists of a basal layer of columnar cells, an intermediate layer of fusiform cells, a layer of incompletely cornified cells and a single surface layer of cells (the periderm). the latter shows central nuclei and distinct cell boundaries. adjacent surface cells. are contiguous and show extensive interdigitations of the lateral cell membranes. the periderm is lost during the first week of postnatal development. the epidermis attains it ... | 1978 | 632218 |
| an autoradiographic study of midbrain-diencephalic projections to the inferior olivary nucleus in the opossum (didelphis virginiana). | techniques of intra-axonal transport were utlizied to elucidate the organization of diencephalic and midbrain projections to the inferior olivary nucleus of the virginia opossum. retrograde transport of horseradish peroxidase injected into the olive suggests that terminals within it arise from the subparafascicular nucleus of the caudal thalamus, the nucleus of darkschewitsch, the fields of forel, the interstitial nucleus of cajal, the periaqueductal grey, the caudal pretectal nucleus, the tegme ... | 1978 | 641221 |
| the organization of olivo-cerebellar projections in the opossum, didelphis virginiana, as revealed by the retrograde transport of horseradish peroxidase. | the retrograde transport of horseradish peroxidase was utilized to map olivo-cerebellar projections in the virginia opossum. the spinal cerebellum (anterior lobe, paramedian lobule and pyramis) receives input from several separate regions in the dorsal accessory nucleus, the medial accessory nucleus and portions of the principal nucleus. evidence is present for a topographical organization whereby specific regions of the olive project to restricted longitudinal zones. the visual-auditory region ... | 1978 | 641222 |
| the north american opossum (didelphis marsupialis) is an excellent model for the study of hemoglobin ontogeny. | 1978 | 721616 | |
| age ratios, weights, and reproduction of the virginia opossum in north louisiana. | 1978 | 750645 | |
| frequency of sarcocystis spp in detroit, metropolitan area, michigan. | a survey of sarcocystis spp in feral animals and in domesticated animals slaughtered in detroit, mi, was undertaken during a 6-month period, april to september, 1973, using histologic and digestion diagnostic techniques. results indicated 75.3% of 789 sheep and 10.8% of 306 lambs were infected. infection in young and adult sheep was low in april (0% of 78 lambs and 6.7% of 62 adult sheep), but increased in july (24% of 90 lambs and 94.1% of 201 adult sheep). high frequency of sarcocystis in summ ... | 1975 | 803806 |
| the vestibular complex of the american opossum, didelphis virginiana. i. conformation, cytoarchitecture and primary vestibular input. | degeneration experiments reveal that the vestibular nerve of the adult opossum distributes to an extensive and diverse area of the brainstem and, as in placental mammals, the traditionally named nuclei do not receive a uniform distribution of primary afferent fibers. nevertheless, such nuclei as well as other nearby cell groups have been considered as vestibular since they share other mutual connections. except for subgroups "l", "g" and the nucleus supravestibularis all of the vestibular subdiv ... | 1977 | 838884 |
| resistance of the opossum (didelphis virginiana) to envenomation by snakes of the family crotalidae. | 1977 | 841589 | |
| the lateral reticular nucleus of the opossum (didelphis virginiana). i. conformation, cytology and synaptology. | 1977 | 864031 | |
| the lateral reticular nucleus of the opossum (didelphis virginiana). ii. connections. | 1977 | 864033 | |
| the second somatic sensory area (smii) of opossum neocortex. | organization of the neocortical second somatic sensory area (smii) of anesthetized virginia opossums has been examined utilizing micro-electrode recording techniques. smii is situated between the first somatic sensory area (smi) medially, and the rhinal fissure laterally. the head representation is located anteromedially within smii, and the hindlimb representation posterolaterally, with the forelimb representation in between. approximately 49% of smii is devoted to representation of the head, 3 ... | 1977 | 864034 |
| the nucleus corporis pontobulbaris of the north american opossum. | the nucleus of the pontobulbar body (pbu) in the north american opossum is located, for the most part, adjacent to the motor root of the trigeminal nerve. material prepared by degeneration and autoradiographic methods shows that the pbu receives projections from the facial motor-sensory cortex, red nucleus, spinal cord and cerebellum. the latter fibers probably take origin within the fastigial nucleus. each of the afferent connections ends in a restricuted part of the pbu, but there is considera ... | 1977 | 903428 |
| high tolerance to snake venom by the virginia opossum, didelphis virginiana. | 1976 | 960117 | |
| the amino-acid sequence of the alpha-crystallin a chains of red kangaroo and virginia opossum. | the amino acid sequence of the a chain of the eye lens protein alpha-crystallin from the red kangaroo (macropus rufus) was completely determined by manual edman degradation of tryptic, thermolytic and cyanogen bromide peptides. the sequence of the alpha-crystallin a chain from the virginia opossum (didelphis marsupialis) was deduced from amino acid analyses and partial edman degradation of peptides. the 173-residue a chains of kangaroo and opossum differ in six positions, whereas comparison with ... | 1976 | 964255 |
| fine structure of the retinal epithelium and tapetum lucidum of the opossum (didelphis virginiana). | the fine structure of the retinal epithelium has been studied by electron microscopy in the opossum (didelphis virginiana). the retinal epithelium, over most of the retina, is typical of that in other vertebrates and consists of a single layer of heavily pigmented, cuboidal cells. these cells display extensive basal (scleral) infoldings and numerous apical (vitreal) processes which enclose photoreceptor outer segments. a semicircular area of the retinal epithelium in the superior fundus is furth ... | 1976 | 966288 |
| primary isolation of mycobacterium avium complex-serotype 6 on blood agar. | mycobacterium avium complex-serotype 6 was isolated in pure culture on blood agar plates from inocula taken from the heart blood, lungs, liver, kidneys, and spleen of a naturally infected captive female opossum (didelphis marsupialis virginiana). repeat cultures from stored tissues and transfer of colonies from original blood agar plates revealed that the mycobacterium grew on tryptose, brilliant green, eosin-methylene blue. sabouraud glucose, and mycobiotic agar plates and in fletcher leptospir ... | 1976 | 972192 |
| observations on the involvement of wildlife in an epornitic of chlamydiosis in domestic turkeys. | in an investigation of potential wildlife reservoirs of chlamydia psittaci at the site of an acute, highly fatal epornitic of chlamydiosis in domestic turkeys in texas, various species of wild birds and rodents were captured and tested for chlamydial serum antibodies and chlamydiae in their tissues. thirteen (65%) of 20 blackbirds (agelaius sp), 4 (44%) of 9 killdeer (oxyechus vociferus), 3 (27%) of 11 sparrows (passer sp) and 1 of 4 mourning doves (zenaidura macroura) were seropositive, but chl ... | 1976 | 988009 |
| retinofugal pathways in two marsupials. | autoradiographic and anterograde degeneration tracing methods were used to study and compare the organization of retinofugal pathways in two marsupial opossums, didelphis virginiana and marmosa mitis. seven identical retinal targets were demonstrated for each opossum. these include: (1) the suprachiasmatic nucleus of the hypothalamus, (2) the dorsal and (3) ventral lateral geniculate nuclei, (4) the lateral posterior nucleus, (5) the pretectal complex, (6) the superior colliculus and (7) the acc ... | 1976 | 993375 |
| vaccination of foxes against rabies using ingested baits. | a method for immunizing foxes against rabies was evaluated. fifteen of 36 red foxes (vulpes fulva) fed baits impregnated with modified live virus rabies vaccine developed serum rabies neutralizing antibody. the vaccine-bait proved unstable when held at 4 c or 25 c for 96 hours prior to feeding. for safety testing the vaccine virus was administered to opossums (didelphis virginiana), cotton rats (sigmodon hispidus), hamsters (mesocricetus auratus), and chickens (gallus domesticus) in either liqui ... | 1975 | 1097743 |
| uterine proteins in the marsupial, didelphis marsupialis virginiana, during gestation. | 1975 | 1110467 | |
| the inferior olivary nucleus of the opossum (didelphis marsupialis virginiana), its organization and connections. | although the inferior olivary nucleus of the opossum is small, sections stained either for nissl substance, normal axons or cholinesterase activity reveal distinct medial, dorsal and principal nuclei. the medial nucleus contains three major subdivisions (labelled a, b, c after bowman and sladek, '73) and a group of neurons which is comparable to the cap of kooy. in contrast to the cat and monkey, the major portion of the "medial" nucleus (subgroup a) lies lateral to the principal nucleus in rost ... | 1975 | 1123465 |
| methods for obtaining neonates of known age from the virginia opossum (didelphis marsupialis virginiana). | postlactational estrus occurred in the opossum 6-17 da (mean 10.08 +/- 3.2da) after sucklings were removed from the pouch 1-60 da postpartum. this estrus occurred somewhat earlier in females whose young were removed later than 24 hr postpartum, rather than within the first 24 hr. thirteen litters (37% conception) resulted from 35 initial attempts at breeding during postlactational estrus. three of 5 females conceived when litters were removed twice in succession. the tendency forindividual femal ... | 1975 | 1152417 |
| leptospirosis in wildlife in brazil: isolation of a new serotype in the pyrogenes group. | a new leptospiral serotype in the serogroup pyrogenes is described. the strain was isolated from one gray "four-eyed" opossum (philander opossum). it is proposed that the serotype be designated guaratuba, strain an-7705. the isolations of serotypes ballum from the south american field mouse (akodon arviculoides), szwajizak and icterohaemorrhagiae from the north american opossum (didelphis marsupialis), and grippotyphosa from many other wild animal species as well as domesticated animals are also ... | 1975 | 1163877 |
| the primary structure of the myoglobin of didelphis marsupialis (virginia opossum). | 1975 | 1164514 | |
| a field study of anatrichosoma infections in the opossum, didelphis virginiana. | 1975 | 1165567 | |
| development of the neonate opossum (didelphis virginiana). | this study describes the postnatal growth and development of the opossum (didelphis virginiana). measurements were made weekly on 6 young opossums between 50 and 189 days following birth. these measurements included: total length, length of ear and tail, and length of front and rear appendages. body weight measurements were extended to 233 days. the mean body weight at 50 days was 14.1 g, which increased rapidly to 2,560 g at 233 days. | 1975 | 1182241 |
| the postnatal development of the liver in a marsupial, didelphis virginiana. 2. electron microscopy. | the postnatal development of the liver has been examined with the electron microscope in 15 groups of young opossums. at birth, hepatic cells show little organization and large islands of haemopoietic elements occur between clusters of hepatic cells. hepatocytes appear small and contain an abundance of granular endoplasmic reticulum. the cytoplasm is also characterized by scattered lipid droplets of varying sizes. canaliculi occasionally are found between hepatocytes. only a few scattered lining ... | 1975 | 1184456 |
| megakaryocytopoiesis in the liver of the developing opossum (didelphis virginiana). | the development of hepatic megakaryocytes has been examined in the livers of 35 young opossums at four different stages of postnatal development. megakaryocytopoiesis is carried out within the sinusoidals and there appears to be a close relationship between the young megakaryocytes and the sinusoid lining cells. megakaryocytes in the opossum are relatively small and lack the degree of nuclear complexity seen in other species. both the nucleus and the cytoplasm undergo sequential maturational cha ... | 1975 | 1201961 |
| corticobulbar fibres in the north american opossum (didelphis marsupialis virginiana) with notes on the tasmanian brust-tailed possum (trichosurus vulpecula) and other marsupials. | corticobulbar projections have been studied in the american opossum by both degeneration and autoradiographic methods and, for the most part, the results confirm our earlier observations (martin & west, 1967; martin, 1968). however, we have obtained evidence for certain connexions not previously described and have delineated the origin(s) of several connexions more precisely by paying particular attention to the degeneration present at thalamic levels in all cases and by the use of autoradiograp ... | 1975 | 1213949 |
| primary afferent fiber distribution at brachial and lumbosacral spinal cord levels in the opossum (didelphis marsupialis virigniana). | this paper describes the spinal cord distribution of primary afferent fibers from forelimb and hindlimb in the north american opossum. fibers entering the cord distribute to all ipsilateral laminae (i-ix) within their segment of entry, often have a small crossed projection to the contralateral dorsal horn, and extend as well into adjacent segments of lumboseacral and cervical enlargements. segmentally derived afferents have a longitudinal extent of up to 10 segments into laminae vi and vii, of 5 ... | 1975 | 1225464 |
| cortical and brain stem projections to the spinal cord of the american opossum, didelphis marsupialis virginiana. | the present report describes the results of experiments designed to study supraspinal systems in the american opossum by several techniques. the data indicate that although spinal fibers from the opossum motor-sensory cortex are small and limited in their distribution, those from the brain stem are comparable in their origin, course, caudal extent and distribution to those described for placental mammals. such results support the use of the opossum as an experimental animal for nervous system re ... | 1975 | 1225466 |
| pre- and postnatal development of lactate and malate dehydrogenases in the marsupial didelphis marsupialis virginiana. | 1975 | 1237386 | |
| opossum somatic sensory cortex: a microelectrode mapping study. | organization of opossum somatic sensory cortex has been investigated utilizing closely spaced microelectrode penetrations (0.25-0.5 mm apart) and delicate mechanical stimulation of body surfaces including the facial vibrissae. results may be summarized as follows: (1) the general organization of somatic sensory cortex, as originally defined by lende ('63a) has been confirmed; (2) a double representation of the contralateral mystacial vibrissae and rhinarium, implicit in lende's original data, wa ... | 1976 | 1245614 |
| cellular mechanisms involved in cyclic stromal renewal of the uterus. i. the opossum, didelphis virginiana. | at the close of a uterine cycle, the remodelling of the endometrial stroma of the north american opossum involves removal of extracellular material by macrophages. this study provides cytochemical and ultrastructural evidence which indicates that the laden macrophages are eliminated from the endometrium through emigration across the glandular and luminal epithelia. during diestrus or the early postpartum period, the abundant uterine glands relinguish their secretory function to acquire a transie ... | 1976 | 1252015 |
| cerebello-olivary fibers: their origin, course and distribution in the north american opossum. | although degeneration techniques suggest that cerebello-olivary fibers are limited in their origin and distribution, horseradish peroxidase and autoradiographic experiments make it clear that they arise within all cerebellar nuclei and project to most, if not all, areas of the contralateral inferior olive. autoradiographic preparations show that cerebello-olivary fibers are highly ordered and suggest that the dentate nucleus projects primarily to the principal olive, the interpositus anterior re ... | 1976 | 1253856 |
| efferent connections of the caudate nucleus in the virginia opossum. | the efferents of the opossum's caudate nucleus were investigated by charting the the fiber degenerations produced by electrolytic lesions in various parts of this nucleus. by the aid of a modified fink-heimer procedure, degenerating fibers were traced from each of the lesions to the small globus pallidus in which they appeared to be distributed in an orderly dorsoventral pattern. fibers from all lesion sites in the caudate nucleus were found to terminate in the entopedunucular nucleus. in the su ... | 2005 | 1262560 |
| laterality and topography of cerebellar cortical efferents in the opossum (didelphis marsupialis virginiana). | 1976 | 1268704 | |
| hemoglobins of the opossum (didelphis virginiana kerr). i. developmental changes from yolk sac to definitive erythropoiesis. | in 5- to 7-da old opossum pouch young, hemoglobins were observed. the "primitive" species i, ii, and iv were shown to be electrophoretically distinct from the adult hemoglobin iii. hemoglobin i was detectable until the 7th postnatal da. hemoglobins i, ii, and iv were detected only during the period when yolk sac-derived primitive erythroblasts were seen in circulation, ei, until the 13th postnatal da, but in decreased amounts from the 6th to 13th da. the electrophoretic pattern of hemoglobin of ... | 1976 | 1271732 |
| a light-microscopic immunocytochemical study of the endocrine pancreas in the australian brush-tailed possum (trichosurus vulpecula). | the endocrine pancreas of the australian brush-tailed possum (trichosurus vulpecula) was investigated by means of immunocytochemistry using the avidin-biotin-peroxidase technique. this was a light microscopic study using this established technique. serial paraffin sections were stained individually with primary antibodies for glucagon, insulin, somatostatin, and pancreatic polypeptide (pp), showing the same islet. cells immunoreactive to glucagon, insulin, somatostatin and pp were found in endoc ... | 1992 | 1380858 |
| the response of rubrospinal neurons to axotomy at different stages of development in the north american opossum. | rubral axons can grow around a lesion of their pathway in the thoracic spinal cord of developing opossums and a critical period exists for that plasticity. the critical period probably begins when rubral axons first grow into the thoracic cord, and it extends until approximately postnatal day 30. we previously noted that most rubrospinal neurons die after transection of their axon during the critical period, suggesting that plasticity results primarily from growth of axons not damaged by the les ... | 1992 | 1383556 |
| immunohistochemical localization of relaxin in the reproductive system of the female opossum (didelphis virginiana). | relaxin-immunoreactivity was demonstrated in the cytoplasm in the luteal cells from pregnant and lactating opossums. immunoreactivity for relaxin was not demonstrated elsewhere in the ovary, in the reproductive tract or in the placenta. the corpus luteum is thought to be the primary source of relaxin in didelphis and in this regard is similar to several eutherian mammals including man. | 1992 | 1416066 |
| the functional morphology of xenarthrous vertebrae in the armadillo dasypus novemcinctus (mammalia, xenarthra). | in order to assess the mechanical properties of xenarthrous vertebrae, and to evaluate the role of xenarthrae as fossorial adaptations, in vitro bending tests were performed on posterior thoracic and lumbar vertebral segments excised from specimens of the armadillo dasypus novemcinctus and the opossum didelphis virginiana, the latter being used to represent the primitive mammalian condition. the columns of the two species were subjected to dorsal, ventral, and lateral bending, as well as torsion ... | 1992 | 1433308 |
| the epidemiology of toxoplasmosis on iowa swine farms with an emphasis on the roles of free-living mammals. | multiparous sows from 19 central iowa swine farms were tested for antibodies against toxoplasma gondii by the modified direct agglutination test. antibody titers of 1:32 or greater were considered positive. rodents, domestic cats, opossums (didelphis virginiana), raccoons (procyon lotor) and striped skunks (mephitis mephitis) were live-trapped on each farm and similarly tested for antibodies. the overall prevalence of t. gondii antibodies in the species tested was 39/273 (14.3%) swine, 31/74 (41 ... | 1992 | 1496780 |
| morphological observations on the harderian gland of the north american opossum (didelphis virginiana). | the harderian gland of the north american opossum (didelphis virginiana) is large and well developed, despite the absence of a nictitating membrane in the adult of this species. the elongate glands are surrounded by a delicate connective tissue capsule from which thin septae extend, subdividing the gland into numerous lobules. the secretory units of the opossum harderian gland are drained by a well defined but not extensive intralobular and interlobular duct system. most of the secretory end pie ... | 1992 | 1510244 |
| retinal topography in the koala (phascolarctos cinereus). | nissl-stained retinal wholemounts were used to investigate the topographical organization of the ganglion cell layer of the koala (phascolarctos cinereus); the visual resolution limit of this animal was subsequently estimated from retinal ganglion cell density data. two types of cells could be differentiated on the basis of their size and staining characteristics: a subpopulation of presumed ganglion cells, consisting of medium to large cells with nissl substance in the cytoplasm and pale unifor ... | 1992 | 1537048 |
| anatomy of the bilioduodenal junction of the opossum. | prevention of reflux is a major function of the terminal biliary duct system at its junction with the duodenum. we examined this area via scanning electron microscopy and light microscopy to explore anatomic features that might play such a role in the virginia opossum, a species with a highly developed sphincter of oddi (so). the terminal apparatus, most of which consists of a dilated extramural ampulla, has a lumen with abundant folds. mucus is produced by the lining epithelium and by a plethor ... | 1992 | 1554107 |
| bacterial flora of the gastrointestinal tract of opossums. | the bacterial flora of the stomach, small intestine, cecum and bile from 20 healthy opossums (didelphis virginiana) captured from the wild was studied. results showed that their gastrointestinal flora was similar to that found in other small mammals but, in addition, opossums are heavily colonized by salmonella spp., which might adversely affect their adequacy as laboratory animals for some experimental protocols. | 1992 | 1557901 |
| electrocardiographic and echocardiographic features of trypanosomiasis in dogs inoculated with north american trypanosoma cruzi isolates. | purebred beagles were inoculated with trypanosoma cruzi isolates from a north american opossum or armadillo (tc-w), and dog (tc-d). although tc-d established infection in dogs, the dogs did not develop cardiac abnormalities. dogs inoculated with tc-w developed acute myocarditis associated with increases in p-r interval, atrioventricular block, depression of r wave amplitude and shifts in mean electrical axis. echocardiograms were normal during this stage. three tc-w-inoculated dogs died during t ... | 1992 | 1586022 |
| development of the digestive system in the north american opossum (didelphis virginiana). | 1992 | 1632285 | |
| serologic response of the opossum didelphis virginiana to a temperature-sensitive mutant (ts-4) of toxoplasma gondii. | a study was designed to measure the toxoplasma gondii-specific igm and igg antibody responses of opossums inoculated with tachyzoites of the temperature-sensitive mutant of t. gondii, ts-4, and to examine its persistence in the tissues. four young opossums seronegative for anti-toxoplasma gondii igm and igg antibodies immediately after capture and 4 wk later were injected subcutaneously with 1.8 x 10(6) ts-4 tachyzoites; a fifth opossum (also seronegative) received an injection of saline only. s ... | 1992 | 1635036 |
| fetal nephrotoxicity. | investigation of fetal nephrotoxicity by maternally administered nephrotoxins is hampered by many constraints, including the maternal effects of the nephrotoxin, the ability of the nephrotoxin to cross the placenta and the difficulties associated with direct fetal intervention. in the pouch young of the north american opossum, didelphis virginiana, we describe the toxic effects of a heavy metal on the immature metanephric kidneys. varying doses of uranyl nitrate, a heavy metal salt, were adminis ... | 1992 | 1640562 |
| organization of midbrain catecholamine-containing nuclei and their projections to the striatum in the north american opossum, didelphis virginiana. | presumptive catecholamine (ca) neurons in the opossum midbrain were identified by tyrosine hydroxylase immunohistochemistry. in the midline, small to moderate number of ca cells were present in the rostral third of the nucleus raphe dorsalis and throughout the nucleus linearis. ventrolaterally, such cells were observed in the deep tegmental reticular formation, in all subnuclei of the ventral tegmental area, and in the three subdivisions of the substantia nigra. the ca cells in these areas confo ... | 1991 | 1677010 |
| physiological interactions between enkephalin and excitatory amino acids in the cerebellar cortex of the opossum didelphis marsupialis virginiana. | the opiate peptide enkephalin has been immunohistochemically localized within specific populations of climbing fibers and mossy fibers in the opossum's cerebellum. the intention of the present study was to determine the physiological effects of this peptide on purkinje cell activity as well as to examine interactions between this peptide and the excitatory amino acids glutamate and aspartate. iontophoretic application of enkephalin onto purkinje cells in the posterior lobe vermis and adjacent he ... | 1991 | 1682851 |
| the origins of supraspinal projections to lumbosacral and cervical levels of the spinal cord in the gray short-tailed brazilian opossum, monodelphis domestica. | retrograde tracing techniques were used to identify supraspinal neurons that project to sacral, lumbar and cervical levels of the spinal cord in the gray short-tailed brazilian opossum, monodelphis domestica. injections of fast blue, true blue or wheat germ agglutinin conjugated to horseradish peroxidase into the sacral or lumbar cord labeled neurons in hypothalamic and brainstem nuclei reported to innervate the same levels in other mammals. injections at cervical levels produced extensive label ... | 1991 | 1684917 |
| origins and terminations of bulbospinal axons that contain serotonin and either enkephalin or substance-p in the north american opossum. | we have shown previously that some enkephalin, substance-p, and serotoninergic neurons in the medullary raphe and adjacent reticular formation project to the spinal cord in the opossum. in the present study we have combined the retrograde transport of true blue and immunofluorescence histochemistry to determine whether methionine enkephalin or substance-p containing bulbospinal neurons are serotoninergic. furthermore, we have used the same immunofluorescence protocol to determine whether spinal ... | 1990 | 1691216 |
| isolation from opossum serum of a metalloproteinase inhibitor homologous to human alpha 1b-glycoprotein. | fractionation of opossum (didelphis virginiana) serum with (nh4)2so4, followed by chromatography on deae-sepharose, phenyl-sepharose, and mono q hr 5/5, has resulted in the isolation in homogeneous condition of a metalloproteinase inhibitor designated oprin (opossum proteinase inhibitor). oprin is a single-chain glycoprotein (26% carbohydrate) with an estimated mr = 52,000, pi = 3.5, and e(1%/1 cm) = 11. oprin inhibited snake venom metalloproteinases, but showed no activity on venom serine prote ... | 1992 | 1731898 |
| evidence for new growth and regeneration of cut axons in developmental plasticity of the rubrospinal tract in the north american opossum. | we have shown previously that rubral axons can grow around a lesion of their spinal pathway in the developing opossum and that a critical period exists for that plasticity (martin and xu, dev brain res 39:303, 1988). since most rubrospinal neurons degenerate after axotomy during the critical period, we have proposed that plasticity results primarily from growth of late arriving axons around the lesion rather than regeneration of cut axons (xu and martin, j comp neurol 279:368, 1989). in the pres ... | 1991 | 1761748 |
| the vestibular apparatus of the opossum (didelphis virginiana) prior to and immediately after birth. | the vestibular apparatus of the opossum was examined shortly before and immediately after birth. a band of about 20 sensory cells was observed within the forming utricle by 24 h prior to birth. stereocilia projecting from the apices of the sensory cells appeared intimately associated with a well-defined population of overlying otoliths. these morphological observations suggest that a functional utricle may be present at the time of birth and together with other senses (tactile, olfaction) may ai ... | 1991 | 1781240 |
| nad synthesis in ada deficient erythrocytes of the opossum didelphis virginiana. | 1991 | 1781390 | |
| natural anti-snake venom proteins. | the resistance of several animals to snake venom has been reviewed. some general concepts are introduced to allow the comparative evaluation of the resistance of different animals studied by different investigators. the purification and properties of several factors isolated from the serum of different animals by some researchers are described: trimeresurus flavoviridis (omori-satoh et al., 1972); vipera palaestinae (ovadia et al., 1975, 1977); sigmodon hispidus (pichyangkul and perez, 1981); di ... | 1991 | 1801313 |
| salmonella infection of the biliary and intestinal tract of wild opossums. | bacteriologic cultures were taken from the mesenteric lymph nodes, biliary tract, blood, liver, spleen and pancreas of opossums (didelphis virginiana) obtained directly from the wild for use as research animals. the overall incidence of salmonellosis outside the intestinal tract was 61% among 18 opossums. salmonella was recovered from the gallbladder of six (33%) animals, indicating chronic biliary tract infection. among these six animals, translocation of salmonella to regional lymph nodes was ... | 1991 | 1849588 |
| the origin of serotoninergic projections to the lumbosacral spinal cord at different stages of development in the north american opossum. | we have employed immunohistochemistry and the retrograde transport of fast blue to study the origin of serotoninergic projections to the lumbosacral spinal cord at different stages of development in the north american opossum. a few serotoninergic axons are present in the lumbosacral cord at birth, 12 days after conception, and serotoninergic neurons are numerous in the brainstem where they are present in most, if not all, of the areas which contain them in the adult animals. a few neurons of th ... | 1991 | 1851469 |
| deoxyadenosine triphosphate acting as an energy-transferring molecule in adenosine deaminase inhibited human erythrocytes. | deoxyadenosine triphosphate (datp) is present in adenosine deaminase (ada)-deficient or ada-inhibited human red cells and in the red cells of the opossum didelphis virginiana. in order to investigate the functions of datp in the red cell, red cells were treated with 2'-deoxycoformycin (dcf), a powerful inhibitor of ada, and incubated with phosphate, deoxyadenosine and glucose. these red cells in which atp was almost completely replaced by datp, had the same shape, lactate production, nucleotide ... | 1991 | 1911876 |
| mammary glands in male marsupials. 2. development of teat primordia in didelphis virginiana and monodelphis domestica. | young and adults of both sexes of two didelphid marsupials, didelphis virginiana and monodelphis domestica, were examined externally for evidence of mammary gland development. female young possessed teat numbers typical of adult females (13-15 in d. virginiana; 11-13 in m. domestica). male young showed variable teat numbers which were always low compared with females, with the majority possessing 2-4 in anterior positions. teats were also present in adult males of both species, in similar number ... | 1991 | 1947228 |
| development of catecholaminergic projections to the spinal cord in the north american opossum, didelphis virginiana. | the intent of our study was to determine when catecholaminergic axons grow into each of their adult targets in the spinal cord of the north american opossum (didelphis virginiana) and to identify the origin of catecholaminergic axons in the lumbosacral cord at different stages of development. tyrosine hydroxylase-like immunoreactive axons, presumed to be catecholaminergic, were demonstrated at different stages of development by the indirect antibody peroxidase-antiperoxidase technique of sternbe ... | 1990 | 1971285 |
| characterization of the muscarinic cholinergic receptor in the opossum (didelphis virginiana, kerr) submandibular gland: differences in receptor density and subtype compared with higher mammalian species. | 1. kinetic, saturation and inhibition radioligand binding experiments with [3h]-n-methylscopolamine and [3h]quinuclidinyl benzilate were used to characterize the muscarinic cholinergic receptor in opossum (didelphis virginiana, kerr) submandibular salivary gland membranes. 2. the receptor density in opossum submandibular gland was found to be more than 3-fold higher than in rat, and 22-fold higher than in human, submandibular glands. 3. inhibitor equilibrium dissociation constants for the antago ... | 1990 | 1981346 |
| hypertrophic smooth muscle in the partially obstructed opossum esophagus. the model: histological and ultrastructural observations. | obstruction is a complication of many esophageal diseases, but the morphological changes occurring in the obstructed esophagus are poorly understood. we developed a model of esophageal obstruction in the american opossum, didelphis virginiana. a nonconstricting band around the gastroesophageal junction led to esophageal distention and tortuosity in the weeks following its placement. despite a marked increase of the esophageal circumference, the esophageal wall was not thinned, and the circular m ... | 1991 | 2001825 |
| lung lesions in an opossum (didelphis virginiana) associated with capillaria didelphis. | an opossum (didelphis virginiana) live-trapped on parramore island, virginia was infected with the lung parasite capillaria didelphis. lung lesions associated with this parasite were extensive and consisted of numerous areas with central necrosis deep within the parenchyma. necrotic foci were present around airways and consisted of a mixture of inflammatory cells and cellular debris, adult nematodes and many bipolar eggs. this parasite causes severe verminous pneumonia in the opossum. | 1991 | 2023321 |
| effects of hydrocortisone acetate treatment on the small intestine of the lactent marsupial didelphis albiventris. | when hydrocortisone acetate was administered subcutaneously to the lactent brazilian white belly opossum, it induced precocious intestinal maturation. histological features of the small intestine were reminiscent of those seen in human protein-caloric malnutrition. there were also indications that the glucocorticoid acted as an inducer of the differentiation of paneth, goblet and granulomucous cells within the small intestinal epithelium. in the lactent opossum the small intestine is lined by an ... | 1991 | 2064018 |
| mammary glands in male marsupials: i. primordia in neonatal opossums didelphis virginiana and monodelphis domestica. | neonates of the american didelphid marsupials didelphis virginiana and monodelphis domestica were sexed by karyotype and histologically examined on the day of birth. mammary anlagen were found in both sexes of both species, but the neonatal males had less than one-third of the full female complement of mammary glands. male neonates of both species also had paired scrotal bulges anterior to the genital tubercle but these were never present in females, once again raising the question of whether th ... | 1990 | 2133544 |
| autoradiographic demonstration of specific binding sites for e. coli enterotoxin in various epithelia of the north american opossum. | in the north american opossum, heat-stable specific binding sites for e. coli enterotoxin are observed (i) in epithelial cells lining the small intestine, colon, gall bladder, cystic duct, common bile duct and trachea, and (ii) in epithelial cells forming the duodenal (brunner's) glands, liver, kidneys (metanephros, mesonephros) and testis, as demonstrated by autoradiography. enterotoxin-specific binding sites in the intestinal tract are only found in intestinal epithelial cells with the highest ... | 1990 | 2162736 |
| aerobic bacteria cultured from the mouth of the american opossum (didelphis virginiana) with reference to bacteria associated with bite infections. | the american opossum inflicts bite injuries both when hunted for food and when accidentally provoked when handled in captivity. this study involved aerobically culturing organisms from the mouths of seven wild opossums (didelphis virginiana). isolates included streptococci, coagulase-positive and -negative staphylococci, aeromonas spp., citrobacter freundii, eikenella corrodens, and escherichia coli. | 1990 | 2229365 |
| studies on the energy metabolism of opossum (didelphis virginiana) erythrocytes--vi. de novo purine nucleotide biosynthesis is limited to the final steps of the pathway in vitro. | 1. high pressure liquid radiochromatography was used to show the incorporation of [14c] formate with z-compounds into atp and gtp in opossum erythrocytes. 2. the use of z-riboside with [14c] formate resulted in more extensive labeling of atp than the z-base/[14c] formate combination as substrates for nucleotide biosynthesis. 3. substantial accumulation of zmp and ztp, but no zdp was detected in the chromatograms. 4. atp was unstable in red cells metabolizing in the presence of z-compounds under ... | 2005 | 2253476 |
| host-dependent differences in feeding and reproduction of ixodes dammini (acari: ixodidae). | the frequencies with which adult ixodes dammini spielman, clifford, piesman and corwin feed upon white-tailed deer (odocoileus virginianus), raccoons (procyon lotor), opossums (didelphis virginiana), and domestic cats were compared in a wooded site in northeastern united states. by combining estimates of the quantity of ticks feeding on each host species with host densities, we derived the relative contribution made by each kind of host to the feeding of the tick population. to compare engorgeme ... | 1990 | 2280395 |
| the lamina propria of vertebrate seminiferous tubules: a comparative light and electron microscopic investigation. | the lamina propria of the seminiferous tubules was compared by means of light and electron microscopy in specimens obtained from the following vertebrates: mute swan, northern mallard, blackbird, grey short-tailed opossum, north american opossum, european rabbit, mouse, rat, golden hamster, mini pig, bull, llama, roebuck, horse, coati, cat, dog, java monkey, orang utan. the lamina propria consists of basal lamina, ground substance, collagen fibers, fibroblasts and myofibroblasts. myofibroblasts ... | 1990 | 2281881 |