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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, ...19957780016
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 ...19957598539
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 ...19968841919
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 ...19968771393
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 ...19968870077
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 ...19968922678
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 ...19968905590
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 ...19968905136
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 ...19968886961
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 ...19968771392
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 ...19968693068
central ph chemosensitivity in the newborn opossum monodelphis domestica. 19969030301
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 ...19968870085
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 ...19968800425
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 ...19968789810
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 ...19968762161
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 ...19968725306
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 ...19968856903
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 ...19968724178
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 ...19968788205
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 ...19968870084
hormones of oestrus and ovulation and their manipulation in marsupials.oestrus and ovulation occur spontaneously in the majority of marsupials, with behavioural oestrus usually occurring 1-2 days before ovulation. the hormone changes that occur at this time have been described in the most detail for the monovular tammar wallaby macropus eugenii. the respective roles of the graafian follicle, corpus luteum and the pituitary in the events leading up to oestrus and ovulation in this species are also reviewed. recently, various protocols have been developed for superov ...19968870088
mammalian oocyte organelles with special reference to pleomorphic mitochondria and vacuole formation in marsupials.marsupial oocytes are larger and have a thinner zona than eutherian oocytes; and the ooplasm becomes almost completely filled with empty-looking vacuoles the contents of which have, so far, defied histochemical analysis. in the opossum, monodelphis domestica, apart from orthodox mitochondria, a 'hooded' form is found occasionally in young primary oocytes, and a novel 'spiked' form-which is very elongate and has longitudinally-running filaments attached to the outer membrane--is found in mature o ...19968870075
cytoplasmic maturation of the marsupial oocyte during the periovulatory period.during the period immediately before ovulation, the oocytes of most eutherian and marsupial mammals complete the first meiotic maturation division and extrude the first polar body. in marsupials, this phase of nuclear maturation is accompanied by an increase in size of the egg and maturation of cytoplasmic components. oocytes from at least four marsupial species, trichosurus vulpecula, macropus eugenii, bettongia penicillata and monodelphis domestica, continue to grow after formation of the foll ...19968870076
culture of preantral ovarian follicles in the grey, short-tailed opossum, monodelphis domestica.a culture system designed to support the development of individual preantral mouse ovarian follicles has been employed to study follicle growth in the new world marsupial species monodelphis domestica. preantral follicles were isolated mechanically and cultured individually in microdrops under oil. preliminary results indicate that follicle growth was positively correlated to the concentration of follicle-stimulating hormone (fsh) provided, with 1.0-1.5 iu fsh ml-1 producing the best results. in ...19968870078
populations of myelinated nerve fibers in the c8 and l4 ventral and dorsal roots in the opossum, monodelphis domestica.a quantitative light-microscopic analysis of the ventral and dorsal roots at the c8 and l4 segments of the spinal cord was made in the opossum, monodelphis domestica, to evaluate the number of myelinated fibers and their class distribution, and will serve as a baseline to a study of myelinogenesis in that species. in male opossums, the c8 ventral root comprises an average of 595 myelinated fibers (70.3% alpha: 29.7% gamma) and the dorsal root 1,124 fibers (29.4% type i: 41.2% type ii: 29.4% type ...19968870787
synaptogenesis in the neocortical anlage and early developing neocortex of rat embryos.the recent finding of synapses in monodelphis domestica (south american grey short-tailed opossum) before the establishment of the cortical plate raises the question of whether this finding is species-specific. therefore, the establishment of the first synapses in the developing neocortex has been studied in the sensorimotor cortex of rat fetuses with a gestational age ranging from embryonic day 12 (e12) to birth. at e14, we found well-defined synapses with postsynaptic thickening and containing ...19968960293
plasma protease inhibitor (pi) system in the laboratory opossum, monodelphis domestica.protease inhibitor (pi) polymorphism was observed in the laboratory opossum, monodelphis domestica, by either one-dimensional acid polyacrylamide gel electrophoresis (page; ph 4.6) or isoelectric focusing (ph 3.5-5.0) followed by immunoblotting with rabbit antiserum to human alpha 1-antitrypsin; but acid page produced superior resolution of the pi proteins. family studies demonstrated an inheritance of nine codominant autosomal alleles, pid, pie, pif, pig, pih, pii, pij, pik, and pim, and a popu ...19968978911
ontogeny of cholecystokinin binding sites in the hindbrain of the laboratory rat.studies in our laboratory have revealed a robust, transient expression of cholecystokinin binding sites in the facial motor nucleus during development in the brazilian opossum, monodelphis domestica. to investigate the ubiquity of this phenomenon, we have performed receptor autoradiography on the hindbrains of embryonic and neonatal rat pups. cholecystokinin binding sites are present at very low levels in the embryonic day-16 rat hindbrain, but binding sites are abundant prior to birth. the grea ...19968724646
epidermal urocanic acid and suppression of contact hypersensitivity by ultraviolet radiation in monodelphis domestica.a single specific epidermal photoreceptor for the immunosuppressive action of uv radiation has not been defined, although separate evidence is accruing in favour of each of two candidates, trans-urocanic acid and dna. in monodelphis domestica, specific photoreactivation repair of uv radiation-induced pyrimidine dimers has been shown to abrogate the suppression of contact hypersensitivity (chs), thus suggesting that dna is the target for this impairment. however, the both haired and hairless mice ...19968620096
structure and chemical coding of human, canine and opossum gallbladder ganglia.immunohistochemistry and cholinesterase histochemistry were used to evaluate the structure and neurotransmitter content of the ganglionated plexuses of the human, canine, and opossum (monodelphis domestica) gallbladders. in each species, the ganglionated plexus consisted of small (mean approximately 4 neurons/ganglion), irregularly dispersed ganglia that were interconnected by bundles of nerve fibers. the density of ganglia was about ten-fold higher in the opossum than in the human or the dog. i ...19968625395
identification of evolutionary conserved regulatory sequences in the 5' untranscribed region of the neural-specific ubiquitin c-terminal hydrolase (pgp9.5) gene.the structure at the 5' end of the gene encoding neural-specific protein gene product 9.5 (pgp9.5) has been compared between two evolutionary distant species: the human and monodelphis domestica. in contrast to the highly conserved coding sequences of the gene, only a 48% identity was found across a 1-kb stretch of 5' untranslated and untranscribed dna. promoter function studies performed on the human sequence identified a 233-bp cpg-rich minimal promoter. truncation mutagenesis revealed the pre ...19968522974
subclasses of vomeronasal receptor neurons: differential expression of g proteins (gi alpha 2 and g(o alpha)) and segregated projections to the accessory olfactory bulb.differential expression of g proteins (gi alpha 2 and g(o alpha) and the separate central projections of gi alpha 2- and g(o alpha)-immunoreactive (ir) vomeronasal receptor neurons were investigated in the mouse and rat using immunocytochemical methods. in the vomeronasal organ (vno), receptor neurons with their cell bodies located in the middle layer (middle 1/3) of the vomeronasal sensory epithelium express gi alpha 2. axons of these gi alpha 2-ir neurons can be followed from vno to the anteri ...19968782871
ultrastructural study of ensheathing cells in early development of olfactory axons.ultrastructural observations in the grey short-tailed opossum (monodelphis domestica) and rat revealed that ensheathing cells were intimately related to the early formation of olfactory axons. whilst the axons were still in the olfactory epithelium, they were enveloped by ensheathing cell processes which formed a cradle-like structure on the basal side of the epithelium. continued downgrowth of the axons towards the lamina propria resulted in an evagination with the ensheathing cell process or c ...19968873986
evolution of transthyretin gene expression in the liver of didelphis virginiana and other american marsupials.the occurrence of the thyroid hormone-binding plasma protein transthyretin in the bloodstream was investigated for four american marsupial species. serum samples were analyzed by incubation with radioactive t4, followed by electrophoresis, then autoradiography, and western blotting. transthyretin was found in serum from monodelphis domestica, didelphis virginiana, caluromys lanatus, and dromiciops australis. for unambiguous identification, transthyretin from d, virginiana was purified from serum ...19968754780
development of olfactory glomeruli: temporal and spatial interactions between olfactory receptor axons and mitral cells in opossums and rats.mitral cells are the primary output neurons of the vertebrate olfactory bulb and are major recipients of sensory input from the periphery. the morphogenesis of mitral cell dendrites was followed to elucidate their early spatial and temporal interactions with olfactory receptor neurons and glia during the construction of olfactory glomeruli. monodelphis domestica, a marsupial born at an extremely immature stage, and rats were examined. mitral cells were retrogradely labeled by application of the ...19968725290
skilled forelimb movements in prey catching and in reaching by rats (rattus norvegicus) and opossums (monodelphis domestica): relations to anatomical differences in motor systems.traditional anatomical/behavioral classifications suggest that rats and opossums have simple motor systems and are impoverished with respect to their ability to make prehensile movements. nevertheless, the motor system in rats and opossums represent extremes in relative size and complexity suggesting that a behavioral analysis of the movement competencies of these species will provide insights into the significance of such anatomical differences. this paper examines the movements that the two sp ...19968883828
development of the anterior commissure in the opossum: midline extracellular space and glia coincide with early axon decussation.while the anterior commissure has been shown to be an important route of information transfer in the forebrain, relatively little is known about its anatomical development. glial substrates and extracellular spaces have been associated with the maturation of other large-fiber tracts, such as the corpus callosum and retinofugal pathway. the present study examined early stages in the maturation of the commissure in the gray short-tailed opossum, monodelphis domestica. monodelphis offspring are bor ...19979087892
ontogeny of androgen receptor-like immunoreactivity in the reproductive tract of male monodelphis domestica.the distribution of nuclear androgen receptor-like immunoreactivity was studied in the reproductive tract of the developing and adult gray short-tailed brazilian opossum (monodelphis domestica), using the well-characterized rabbit polyclonal androgen receptor antibody, pg21. androgen receptor-like immunoreactivity was first detected on the fifth day of postnatal age, in the mesenchymal tissues of the ductus deferens, gubernaculum testis, inguinal, and scrotal areas; the urogenital sinus; and the ...19979096865
novel strategies for eutherian x marsupial somatic cell hybrids: mapping the genome of monodelphis domestica.two hundred thirty-seven independent somatic cell hybrids have been obtained between opossum (monodelphis domestica) splenocytes, bone marrow cells, or primary fibroblasts, and hprt-deficient or tk-deficient chinese hamster, mouse, american mink, or common vole fibroblast lines. because extreme segregation and fragmentation of marsupial chromosomes commonly occurs in eutherian x marsupial somatic cells hybrids, we developed a rapid primary screening method that enables the identification of prim ...19979186503
chemosensory and cholinergic stimulation of fictive respiration in isolated cns of neonatal opossum.1. the aim of the present experiments was to characterize the central chemical drive of fictive respiration in the isolated cns of the newborn opossum, monodelphis domestica. this opossum preparation, in contrast to those of neonatal rats and mice, produces respiratory rhythm of high frequency in vitro. 2. fictive respiration was recorded from c3-c5 ventral roots of the isolated cns of 4- to 14-day-old opossums using suction electrodes. at room temperature (21-23 degrees c) the frequency of resp ...19979192313
male gray short-tailed opossums (monodelphis domestica) receive penile intromissions when treated with estrogen and progesterone in adulthood.following treatment with estradiol and progesterone, gonadectomized male as well as female gray opossums received penile intromissions from intact stimulus males. intromission was possible in male gray opossums because, like marsupials of both sexes, they possess a single cloaca-like anogenital opening. all subjects that allowed intromission showed anogenital dragging just prior to intromission. while intromission latency was similar in tests involving male and female subjects, total intromissio ...19979213142
effects of unilateral olfactory deprivation in the developing opossum, monodelphis domestica.unilateral naris closure in young rodents leads to striking alterations in the development of the ipsilateral olfactory system. one of the most pronounced effects is a 25% reduction in the size of the experimental olfactory bulb, a change that stems in part from decreased cell survival. since naris occlusion in rodents alters the system more during development than in adulthood, we investigated the consequences of olfactory deprivation in a species that is born in a very immature state, monodelp ...19979322159
nonshivering thermogenesis in marsupials: absence of thermogenic response to beta 3-adrenergic agonists.the status of nonshivering thermogenesis (nst) in marsupials remains controversial. although morphological studies have failed to find evidence for the presence of brown adipose tissue (bat) in adults or juveniles of species from all extant families of marsupial, a number of studies have investigated the metabolic response of marsupials to noradrenaline (na) and yielded conflicting results. in eutherian mammals, na stimulates nst in bat by acting on beta 3-receptors, and in the experiments repor ...19979172391
recombination activating gene-1 of the opossum monodelphis domestica. 19979038106
photorepair of ultraviolet radiation (uvr)-induced pyrimidine dimers in lens epithelial dna of monodelphis domestica.the repair of uv radiation-induced pyrimidine dimers has been measured in lens epithelial dna of the marsupial monodelphis domestica using a pyrimidine dimer-specific endonuclease from micrococcus luteus. approximately 40% of the initially induced dimers were repaired during 90 min exposures to photoreactivating light. this capacity of the lens epithelium to photorepair pyrimidine dimers may provide a means with which to determine whether pyrimidine dimers in lens epithelial dna are involved in ...19979066292
albumin transfer across the choroid plexus of south american opossum (monodelphis domestica).1. blood-cerebrospinal fluid (csf) transfer of various exogenous albumins has been investigated in developing monodelphis domestica (south american grey short-tailed opossum) and compared with the steady-state csf: plasma ratios for endogenous (monodelphis) albumin. ratios for monodelphis albumin and human albumin were similar and were the highest at postnatal day 5 (p5) (48.2 +/- 4.4 and 40.6 +/- 4.5%, respectively). the ratio for bovine albumin was similar to the steady-state ratio for monodel ...19979061648
prolactin-like biological activity in the pituitary glands of the marsupial monodelphis domestica and of the amphibian rana pipiens detected by a colorimetric nb2 lymphoma cell proliferation assay.an inexpensive and reliable colorimetric microplate version of the nb2 lymphoma cell proliferation bioassay for prolactin (prl) was developed and optimized. the useful range of the assay is between 0.1 and 12.8 ng/ml in terms of rat pituitary prl. the assay can accommodate up to 20 microl sample/well. the physiological relevance of the assay was verified by measuring thyrotropin-releasing hormone (trh)-induced secretion of prl in pituitary cultures and in serum samples of neonatal rats. through ...19979034132
didelphid behavior.there are approximately 75 species of american opossums (didelphids). systematic behavioral research has been reported for only a small number of species, namely, monodelphis domestica and didelphis virginiana. observational studies and field reports on several other didelphid species have also been published. the current review covers behavioral studies on didelphids including research on territoriality, reproductive behaviors, parturition, maternal behaviors, nest-building, vocalizations, scen ...19979168270
ontogeny and limb bone scaling in two new world marsupials, monodelphis domestica and didelphis virginiana.this study examines the growth of two species of marsupials who share common ancestry and are born at the same neonatal size of a little less than 1 g. despite this similarity at birth, adult size of these two species differs by about 50 times, with the smaller species believed to be the more ancestral. we quantified the growth in the limb bones (humerus, femur, ulna, tibia, metacarpal, and metatarsal) beginning around 40 days of age until adult size was reached. results indicate that the larger ...19978989872
spermiogenesis and spermiation in a marsupial, the tammar wallaby (macropus eugenii).fourteen steps of spermatid development in the tammar wallaby (macropus eugenii), from the newly formed spermatid to the release of the spermatozoon into the lumen of the seminiferous tubules, were recognised at the ultrastructural level using transmission and scanning electron microscopy. this study confirmed that although the main events are generally similar, the process of the differentiation of the spermatid in marsupials is notably different and relatively more complex than that in most st ...19979147224
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 ...19979184350
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- ...19979066512
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 ...19979027302
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 ...19979051643
the laboratory opossum (monodelphis domestica) in laboratory research. 199711528041
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 ...19979150896
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 ...19979383223
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 ...19979401767
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 ...19979387986
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 ...19979370059
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 ...19979364932
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 ...19979347121
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 ...19979240844
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.19979363598
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 ...19979360317
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 ...19979352103
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 ...19979295147
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 ...19979288772
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 ...19979225163
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 ...19979241631
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 ...19979241630
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 ...19979177557
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 ...19989579400
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 ...19989555018
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 ...19989551979
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 ...19989541264
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 ...19989530819
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 ...19989510954
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 ...19989412512
absence of a significant mixed lymphocyte reaction in a marsupial (monodelphis domestica).previously we reported preliminary results suggesting that the marsupial monodelphis domestica fails to exhibit a mixed lymphocyte reaction with allogeneic lymphocytes. to test whether this observation is simply a matter of a response too weak to detect, but capable of being augmented by immunization, we performed mixed lymphocyte culture tests on 23 of these animals that had been immunized with lymphocytes. despite the fact that all recipients were sensitized to the lymphocytes of the donors, n ...199810090011
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 ...19989624588
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 ...19989754561
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 ...19989713989
the function and structure of the marsupial enamel.the aims of this study are to clarify the structure of tubular enamel and the function of enamel tubules on the marsupial of opossum (monodelphis domestica). almost all enamel prisms, surrounded by interprismatic enamel, ran obliquely from the dentinoenamel junction (dej), and bent near the enamel surface. the enamel tubules are distributed in both enamel prisms and the interprismatic enamel near the dej. from the middle to the surface of the enamel, one enamel tubule ran within a single enamel ...199811063002
vomeronasal organ and its associated structures in the opossum monodelphis domestica.the opossum monodelphis domestica possesses a well-developed vomeronasal system. uptake of chemical stimuli into the vomeronasal organ (vno) involves a stereotypical "nuzzling" behavior. in the present study, ten animals were examined by light and electron microscopy. the peripheral oro-nasal structures that apparently enhance access of solutes into the vno include: (1) two lateral grooves of the ventral rhinarium and a network of channels leading into them, (2) dental gap adjacent to the groove ...19989880164
[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 ...19989691798
development of nadph-diaphorase expression in chemosensory systems of the opossum, monodelphis domestica.using nadph-diaphorase histochemistry, the present study describes development of olfactory and vomeronasal systems in postnatal opossums, monodelphis domestica. nadph-dependent staining is absent at and around the time of birth. by 2 weeks of age and through adulthood, intense staining is seen along the luminal surface of the olfactory epithelium (oe) and of the vomeronasal sensory epithelium (vne), as well as in bowman's glands of the oe. staining of the adult vne is not homogeneous; it is res ...19989804891
low-dose ultraviolet exposure early in development can lead to widespread melanoma in the opossum model.suckling young of opossums (monodelphis domestica) were exposed to ultraviolet radiation (uvr, predominantly uvb: 290-320 nm) in part to determine an optimal protocol for induction and progression of melanoma in this species. in all, 620 litters were introduced to one of seven protocols. the lowest dose (175 j/m2) administered three times a week for almost three weeks led to the highest incidence of melanotic lesions with melanoma potential (8.1%) among young (5-month-old) adults. among 101 much ...19989797719
isolation of mhc class ii dma and dmb cdna sequences in a marsupial: the gray short-tailed opossum (monodelphis domestica).we report the cdna sequences for the dma and dmb family of mhc genes of the gray short-tailed opossum. until now dm sequences were available only in eutherian mammals. the marsupial sequences indicate that both members of the family are old and probably diverged from other classical class ii families about the time of the radiation of jawed vertebrates some 450 million years ago. we examine the evolutionary rates of equivalent sets of classical and nonclassical genes to check for rate heterogene ...19989797408
neurogenesis and migration of receptor neurons in the vomeronasal sensory epithelium in the opossum, monodelphis domestica.the sensory epithelium of the vomeronasal organ (vno) contains primary chemosensory receptor neurons that project to the accessory olfactory bulb (aob). in the present study, neurogenesis and cell migration in the sensory epithelium of the vno were analyzed in opossums (monodelphis domestica) by using bromodeoxyuridine (brdu) labeling. 1) in the vno of normal adult opossums, brdu labeled a small number of cells localized in the basal region of the sensory epithelium. after 1 or 2 weeks of surviv ...19989766405
opossum (monodelphis domestica) terminal deoxynucleotidyl transferase gene. 19989553155
re-establishment of direct synaptic connections between sensory axons and motoneurons after lesions of neonatal opossum cns (monodelphis domestica) in culture.for functional recovery after spinal cord injury, regenerating fibres need to grow and to reform appropriate connections with their targets. the isolated central nervous system of neonatal opossums aged 1-9 days has been used to analyse the precision with which neurons become reconnected during regeneration. in culture these preparations maintain their electrical activity and show rapid outgrowth through spinal cord crushes or cuts. by recording electrically and by staining with horseradish pero ...19989767381
marsupial light chains: complexity and conservation of lambda in the opossum monodelphis domestica.the ig lambda chains in the south american opossum, monodelphis domestica, were analyzed at the expressed cdna and genomic organization level, the first described for a nonplacental mammal. the v lambda segment repertoire in the opossum was found to be comprised of at least three diverse v lambda families. each of these families appears to be related to distinct v lambda families present in placental mammals, suggesting the divergence of these genes before the separation of metatherians and euth ...19989862702
heterogeneity in the accessory olfactory system.the mammalian accessory olfactory bulb (aob) is chemoarchitecturally heterogeneous in that it stains differentially with a number of markers; the receptor cells that project to the aob are similarly heterogeneous. what is the significance of this heterogeneity? we have found that the aob of the gray, short-tailed opossum, monodelphis domestica, stains differentially with a number of 'markers': antibodies to olfactory marker protein (omp) and the alpha subunit of the g protein gi2, the lectin of ...19989759536
three-dimensional visualization of the distribution, growth, and regeneration of monoaminergic neurons in whole mounts of immature mammalian cns.at birth, the opossum, monodelphis domestica, corresponds roughly to a 14-day-old mouse embryo. the aim of these experiments was to compare the distribution of monoaminergic neurons in the two preparations during development and to follow their regeneration after injury. procedures that allowed antibody staining to be visible in transparent whole mounts of the entire central nervous system (cns) were devised. neurons throughout the brain and spinal cord were stained for tyrosine hydroxylase (th) ...19989455902
procedures for whole-mount immunohistochemistry and in situ hybridization of immature mammalian cns.whole-mount labeling techniques for staining in invertebrates or lower vertebrates cannot simply be applied to the mammalian central nervous system (cns) because of its large size. such techniques if possible would offer advantages over conventional methods based on sections since an immediate and 3-dimensional view of the stained components in a transparent cns is provided. it thereby becomes possible to survey and count large number of cells and fibers in their natural relationships. the aim o ...19989473657
cortical perineuronal nets in the gray short-tailed opossum (monodelphis domestica): a distribution pattern contrasting with that shown in placental mammals.extracellular matrix proteoglycans accumulated in perineuronal nets and in certain neuropil zones have been shown to influence the immediate neuronal microenvironment, and to contribute to the chemoarchitectonic characteristics of neuronal networks. studies in different placental mammals, including the human, have suggested that the major principles of extracellular matrix distribution remained constant during phylogenesis of the different mammalian strains. however, the comparison of matrix dis ...19989565318
development of thalamocortical projections in the south american gray short-tailed opossum (monodelphis domestica).we determined the time-course and general pattern of thalamocortical development of monodelphis domestica by tracing projections with carbocyanine dye in fixed postnatal brains between postnatal day 2 (p2) and p30. by p2, the first neurons have migrated to form the preplate of the lateral cortex and have sent out axons into the intermediate zone. by p3, fibers from the preplate of more dorsal cortex have entered the intermediate zone, and, by p5, they reach the primitive internal capsule. crysta ...19989717705
uv-induced melanoma cell lines and their potential for proteome analysis: a review.we have established cell lines from benign cutaneous melanocytic lesions and from melanoma-affected lymph nodes of monodelphis domestica, the laboratory opossum (a south american marsupial now widely maintained in captive colonies for experimental purposes). unlike melanoma cell lines currently available from humans and other mammals, the opossum lines are derived from cells transformed in vivo by experimentally controlled exposure to ultraviolet b (uvb) radiation of known spectral composition. ...19989723165
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