The parotid glands of Tupaia glis were examined by light and transmission electron microscopy. The acinar cells were seromucous in nature, and contained many acidophilic granules with strong affinity for periodic acid-Schiff (PAS) and weak affinity for alcian blue (AB). These granules consisted of a fine granular matrix of moderate density in which a denser corpuscles or semilunar materials were present. Intercalated duct cells had a few fine vesicles, vacuoles and very few dense granules in the apical region. In occasional epithelial cells, acidophilic, PAS-positive and AB-negative bodies with moderate density were observed in the supranuclear region. The striated ducts consisted of columnar light and dark cells containing round or small ovoid granules of moderate density and did not show the granular duct as seen in the parotid glands of kobe mole and tenrec which are placed in the order insectivora.

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During early stages in avian embryogenesis primordial germ cells (PGCs) show a unique migration pathway toward the gonadal anlage through the circulation. In the present study, liposomes consisting of plasmid DNA (pMiwZ; containing lacZ as a reporter) and Lipofectin were injected into the marginal veins of quail embryos during the stages PGCs were circulating in the blood vessels. The lacZ expression was then histochemically detected in the gonads at later embryonic stages, indicating the expression of the injected DNA in PGCs.

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The dermal histology of 9-week-old hairless rats derived from Wistar rats was investigated and compared with that of age-matched Wistar rats. Skin samples were taken from 4 portions: the head, dorsal and ventral skin, and foot pad. The epidermis of the 3 portions other than the foot pad was thicker in hairless rats than in Wistar rats. The hair canals of hairless rats contained lamellar cornified tissues instead of hair, and some of the hair follicles deep in the dermis exhibited cyst formation. S-100-immunoreactive cells were detected in the basal layer of epidermis and their number in hairless rats was greater than that in Wistar rats. Ultrastructurally, electron-lucent cells, i.e. Langerhans cells, which contained Birbeck granules and/or cored tubules, were observed more frequently in the epidermis of hairless rats than in that of Wistar rats. Some cells in one hairless rat, which had similar characteristics to Langerhans cells without Birbeck granules, contained confronting cisternae.

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Adrenal weights and adrenocortical zonation were compared in two inbred mouse strains, C57BL/6J and DDD, which are different in both origin and genetic background. Clear strain and sex differences were observed in the adrenal weight and the morphology of the zona fasciculata, z. reticularis and X zone. DDD adrenals were larger than C57BL/6J ones regardless of sex. The z. fasciculata was thicker in female than male DDD mice. The z. reticularis of DDD males developed nodules at 70 days of age, followed by an increase in size with age, while that of C57BL/6J males did not. Parous females experiencing pregnancy, gestation and lactation also developed similar nodules, but virgins did not. The X zone degeneration occurred earlier in males than in females. This zone disappeared before 5 weeks of age in males but gradually decreased in thickness with age in DDD virgins. The female X zone was thicker and degenerated with vacuolation in DDD, while it was thinner and degenerated without vacuolation in C57BL/6J. Such clear strain differences in the inner cortices, z. reticularis and X zone, suggested that their morphology might be regulated primarily by genetics and modified by endocrinology.

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Dorsal skin reactions to irradiation with two different types of ultraviolet (UV) light sources (sunlight and artificial UV light) were investigated in hairless descendants of Mexican hairless dogs. The total energy dose of solar UV exposure and artificial UV irradiation was 90 kJ/m² and 40 kJ/m², respectively. Histological examinations were done up to 7 days after UV irradiation (7 DAI). At 1 DAI, the solar UV-exposed skin did not show marked changes, while artificial UV irradiated skin exhibited a visible erythematous reaction and prominent histological alterations such as epidermal thickening, appearance of sunburn cells and deformation elastic fibers. At 4 DAI of solar UV-exposure, the skin color became moderately dark and noticeable pigmentation developed in the epidermis. In contrast, at 4 DAI of artificial UV irradiation, there still remained moderate degeneration in the epidermis and dermis, and delayed tanning was weak. At 7 DAI of solar exposure, delayed suntan reactions became more prominent. Histologically, there were heavy pigmentation of melanin granules mainly in the stratum basale. On the other hand, artificial UV irradiated skin showed less pigmentation. Thus, solar exposure provoked remarkable pigmentation while artificial UV irradiation brought about severe sunburn reactions in the dorsal skin of hairless dogs.

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Strain-specific restriction fragments hybridizing to human p53 gene cDNA, which was detected in only particular strains of inbred rat were revealed by Southern blot hybridization of DNAs of various inbred rat strains. Chromosomal location of the strain-specific fragments was determined on rat chromosome 1 between Kal and Pkc loci by linkage analysis using microsatellite marker loci. The fragments were concluded to be a novel p53-related sequence which is present in particular rat strains and absent from the remaining strains.

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Effects of age at first-pairing on the reproductive performance of the gerbil were studied throughout the reproductive life. Six groups of 7-30 female gerbils were paired monogamously with males at different ages. Out of 101 pairs in 6 groups, 79 (78.2%) produced 1 or more litters. The mean litter size at birth and mean weaning rate of 846 litters were 4.4 (totally 3,733 pups) and 67.4% (2,517 pups), respectively. Reproduction was compared in the 6 age groups. The littering rate (No. of females with litters / No. of female paired) was significantly lower in two groups in which mature females were paired with age-matched males (Group 4) or the oldest females with younger, sexually mature males (Group 6). The interval from pairing to the first litter was shortest in two groups in which mature females were paired with one month older, sexually mature males (Groups 3 and 5). Although the oldest pairs (Group 6) produced about 7 litters, the pairs from the other 5 groups produced about 10 or more litters throughout their reproductive life. The weaning rate was significantly higher in Group 6 (the oldest pairs) than in the younger groups. The effects of parity on reproduction were estimated from the data for the 61 pairs which produced more than 8 litters in the 6 groups. The number of pups at birth and the weaning rate were decreased in last 20-30% of the total parity in all 6 groups, although the age at the last litter in all groups was significantly different. The data suggest that any decline in reproduction may be due to not age but parity in the Mongolian gerbil.

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The testes of rats were exposed to a single soft x-ray irradiation at levels of 10, 25 and 63 Gy. Testicular and cauda epididymal weights and their sperm counts were decreased at 7 weeks after the irradiation. Histologically, there was an evidence of interrupted spermatogenesis dose-dependently. Animal mating trails, in which irradiated males were mated with untreated females revealed a slight increase in early stage of postimplantation loss at as low as 10 Gy. There were increases in preimplantation and early stage of postimplantation losses in the group of irradiated at 25 Gy. Infertility occurred in irradiated males at 63 Gy. The effects of irradiation were more severe on the sperm count parameters than on reproductive organ weights, histological examination and reproductive status. The testicular spermatid and epididymal sperm head counts are considered to be useful indicators to detect quantitatively the adverse effects on spermatogenesis.

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A survey of inbred strains of mice revealed genetic variation in DNase II activity in the spleen, liver, kidney, lung, heart, coagulating gland and preputial gland. Since DNase II activities in these tissues were closely correlated to each other, systemic regulation of the enzyme was suggested. The inheritance of quantitative variation in the DNase II activity was studied in a test cross using the spleen DNase II activity level as an indicator of progeny phenotypes. The results showed that the strain difference in DNase II activity was controlled by a single autosomal locus. The locus for the mouse DNase II activity level, designated as Dnl2al, had at least two alleles. The allele Dnl2al^a determines high DNase II activity and occurs in C57BL/6 and C3H/He strains. The other allele Dnl2al^b determines low enzyme activity and occurs in BALB/c and DBA/2 strains.

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Globule leukocytes (GLs) infiltrating in transitional cell hyperplasia and carcinomas of aged BDF₁ mice were pathologically examined. The intracytoplasmic granules of globule leukocytes showed a variety of reactivity to histochemical staining for polysaccharides and were ultrastructurally composed of homogeneous electron dense material, occasionally containing crystaloids or vesicles. The GL infiltrating in tumor tissue is extremely rare.

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Cilia-associated respiratory (CAR) bacillus was detected by means of the reverse transcription (RT)-polymerase chain reaction (PCR), and the results were compared with those of indirect immunofluorescence test (IFAT) for the detection of the organism. In the experimental infections, 15 mice were in contact with mice previously inoculated with CAR bacillus. Three mice each were tested at days 3, 5, 7, 12 and 20 postexposure. On day 3 postexposure, CAR bacillus was detected in oral swab samples from all 3 mice by RT-PCR, but was not detected in any sampling sites from the mice by IFAT. Total numbers of positive samples from nasal, oral and tracheal swabs obtained through the test were 6/15, 14/15 and 8/15, respectively, by RT-PCR, and 2/15, 6/15 and 3/15, respectively by IFAT. For the detection of CAR bacillus in samples from 52 rats, 34 serum antibody negative rats by enzyme-linked immunosorbent assay were also negative by RT-PCR and IFAT except for one sample from the oral cavity, and all serum antibody positive rats were positive for the organism by RT-PCR but it could not be detected in five of them by IFAT. By means of RT-PCR, no differences in the positive rates depending on sampling sites were observed except in one rat. The RT-PCR was found to be a specific, highly sensitive and reliable procedure for detecting CAR bacillus in mice and rats. The oral cavity was the most suitable site for the diagnosis of the early stage of this infection by RT-PCR.

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Peritoneal mast cell hyperplasia was investigated in rats after evoking IgE antibody-antigen reaction. Rats were immunized with antigen and then passively sensitized with monoclonal IgE antibody before antigen challenge. A significant increase in the number of peritoneal mast cells was observed 3 weeks after the antigen challenge in the peritoneal cavity, although the histamine content of the mast cells was decreased significantly. In rats without prior immunization, these changes were not observed. Stimulation with compound 48/80 or calcium ionophore A23187 did not affect the number of mast cells. This model may prove to be a useful tool for studying the mechanisms of mast cell hyperplasia and recruitment of mast cell precursors in vivo.

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We macro- and microscopically examined two cases of congenital visceral transposition (situs inversus totalis) in SD rats. We also investigated the possibility of situs inversus in association with immotile-cilia syndrome. The rats had grown normally with no clinical signs of disease. Although all organs including the vascular system were located opposite to the normal position and displayed a mirror image on macroscopic observation, no abnormality was found in any of the organs on microscopic examination. Electron-microscopic observation revealed in neither animal any structural abnormalities of the cilia and flagella, which are one of the diagnostic characterizations of immotile-cilia syndrome. Congenital transposition of the viscera is rare and there are few reports examining complications with situs inversus in rats. This report will be helpful in accumulating information on this condition.

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Mutant mice characterized by a cream coat and pink eyes were spontaneously discovered among the descendants of Indonesian wild mice (Mus musculus castaneus). This mutant phenotype was controlled by a single autosomal recessive gene that was allelic to the pink-eyed dilution (p) gene. The mutant mouse phenotypically resembled the original p mouse which was the first mutant identified at this locus. Nevertheless, these two alleles differed in origin, a previous report suggesting that the original p allele was derived from Japanese wild mice (M. m. molossinus). Thus the symbol p^cas (pink-eyed castaneus) was proposed for the present mutation allele.

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Ultrastructural characteristics of the dorsal skin of hairless descendants derived from Mexican hairless dogs (3-month-, 1-year-and 5-year-old) were investigated and compared with those of age-matched beagles. Except that beagles had no melanocytes in epidermis, there was no essential difference in ultrastructural characteristics of epidermis between hairless dogs and beagles. In the Stratum basale of epidermis of hairless dogs, a small number of melanocytes and a few Langerhans cell (LC)-like cells were observed among keratinocytes. Melanocytes contained many melanosomes and a few premelanosomes. LC-like cells were characterized by electron-lucent cytoplasm and lobulated nucleus and lacked melanin granules, tonofilaments and desmosomal attachments. Unlike LC in humans and rodents, these LC-like cells did not contain Birbeck granules. Although age-related ultrastructural changes of dorsal skin were generally not clear both in hairless dogs and in beagles, cells containing melanin granules were not infrequently observed among dermal collagen bundles in 5-year-old hairless dogs.

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