Arthritis was produced in beagles by the immunological reaction to bovine serum albumin (BSA). Dogs immunized with BSA showed the development of delayed type-hypersensitivity response to BSA and the significant increase in the titer of serum anti-BSA antibodies. The development of arthritis and the increase in a number of nucleated cells in synovial fluid were observed by the injection with BSA into the knee joints of immunized dogs. The synovial membrane of BSA-injected joints revealed a remarkable villous hyperplasia of membrane, and an infiltration of lymphocytes and plasma cells around vessels, resulting in a lymphoid nodule-like formation. The depositions of IgG and C3 on the surface of the synovial membrane were also observed in BSA-injected joints. Histopathological and immunopathological findings indicated that the immune response to BSA in the knee joints could induce a rheumatoid arthritis like chronic synovitis in dogs.

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The morphogenesis of the photoreceptor cells in the retinas of C₃H mice carrying the rd gene and C₅₇BL mice carrying the normal gene was compared, and retinas of the C₃H mutants (C₃H-lpr/lpr, -lpr^cg/lpr^cg, and -lpr/lpr·gld/gld) defective in apoptosis through the Fas system were examined. In the C₅₇BL retina, the inner and outer nuclear layers were separated at 8 days of age, and the photoreceptor inner and outer segments began to grow between 8-11 days after birth with their most rapid growth occurring between 14-17 days of age. In the C₃H retina, the development was comparable to that of the C₅₇BL retina at 8 days of age but the reduction in thickness of the outer nuclear and photoreceptor layers was noted at 11 days of age, and the outer nuclear layer became reduced to only a few nuclei in thickness at 14 days, being completely missing or reduced to a single row of cells at 20 days. The degeneration was by an apoptotic mechanism as confirmed morphologically and by the TUNEL method. In all the C₃H mutant retinas examined over 24 days of age, the complete depletion of the outer nuclear layer or reduction to a single row comparable to 20-day-old C₃H mice was seen. The rd gene action is therefore independent of Fas/Fas ligand-medicated apoptosis.

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Changes in body weight (25-175 days old, every 10 days) and weights of various organs (70, 105, 140 and 175 days old), i.e., cerebrum, cerebellum, pituitary gland, thyroid gland, thymus, heart, liver, spleen, adrenal gland, kidney, seminal vesicle, prostate, epididymis, testes, bulbourethral gland and ovary, of Ishibashi (IS) rats with growth, which are model animals for congenital vertebral malformation (spontaneous kyphoscoliosis) were examined as compared with Brown Norway (BN) rats, which are genetically irrelevant to IS rats, and also with hybrid rats (IBF₁ rats) which are between IS and BN rats. The experimental results showed that body weight and weights of various organs except cerebrum, cerebellum and thymus were greater in IS rats than in BN rats, and body weight and weights of various organs of IBF₁ rats were intermediate between the two strains of rats.

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Auditory brainstem response (ABR) is a useful method in evaluating auditory function in human. To investigate the ABR threshold is more effective than to pursue the trends in each component of ABR. In this study, tone burst sound stimuli were employed and the ABR threshold shift caused by kanamycin administration was investigated in dogs. In a series of monitoring of ABR against short-period auditory lesions, changes in the ABR waveform after intravenous administration of kanamycin were detected. These changes returned gradually and were reversible. The changes in ABR against long-period auditory function disorder were perceived by an increase in the ABR threshold. The ABR threshold shift occurred earlier in the high frequency sounds than in the lower frequency sounds. This is why amino glycoside antibiotics damage the cochlear hair cells in the basal layer and lead to the loss of hearing selectively for high frequency tones. These findings suggest that tracing of the ABR threshold by tone bursts could provide information that has a specificity for frequency in hearing tests and is a useful method in clinical veterinary medicine or/and toxicological tests.

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In this study, myocardial damage in the D-variant of encephalomyocarditis (EMC-D) virus-induced myocarditis has been investigated consecutively by measuring serum creatine phosphokinase (CPK) activity. CPK activity in 8 week-old male BALB/cAJcl mice inoculated with EMC-D virus increased to a peak at 4 or 5 days postinoculation (DPI) and then gradually decreased. The CPK activity rose again after 7 DPI until it reached a second peak. In view of the kinetics of CPK activity, two-phase (early and late phase) myocardial damage in EMC virus infection were considered. In the late phase, an increase in cellular infiltration in the myocardium and a decrease in viral titer in the heart were observed. It was therefore suspected that the increase in CPK in the late phase may be caused by cellular infiltration, but not by viral replication. In our results, we suggested that a serial measurement of serum CPK activity might be a useful method for throwing more light on the myocardial damage caused by the autoimmune response. We also used a pathological (TUNEL) method to detect apoptotic cells and some apoptotic myocytes in the myocardium in late phase EMC virus-induced myocarditis.

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Syrian hamsters of the APA strain (APA hamsters) develop spontaneous mesangial thickening in the renal glomeruli from an early age. They also develop focal and segmental glomerulosclerosis (FSG) at and after 6 months of age. In this study, histopathological, histochemical and electron microscopical examinations were conducted to clarify the age-related renal glomerular changes in spontaneous FSG of APA hamsters. Histopathological analysis revealed that expansion of the mesangial region and thickening of the glomerular basement membrane (GBM) in the glomeruli of APA hamsters progressed with age. These age-related changes appeared earlier in male animals. Immunohistochemical analysis suggested that type IV collagen was responsible for the expansion of the mesangial region and thickening of the GBM. In lectin histochemical analysis, positive sites for WGA with and without neuraminidase pretreatment and PNA with neuraminidase pretreatment were detected mainly in podocytes and were expanded with age. Ultrastructurally, the increase in basement membrane-like materials in the mesangial matrix, development of intracellular organella of mesangial cells and migration of a part of the mesangial cell cytoplasm into the GBM were observed at and after 6 months of age. These features suggested that mesangial cells played an important role in the age-related expansion of the mesangial region and thickening of the GBM.

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Blood from an individual quail embryo at stages 13-16, when primordial germ cells (PGCs) were in circulation, was taken from its marginal vein and transfused into the marginal vein of a chick embryo at stages 13-16. Both donor and recipient embryos were cultured in vitro until day 8 of development and their sex was determined by morphological and histological observations of the gonads. Sections of recipient gonads were stained immunohistochemically with QCR1 monoclonal antibody positive for quail PGCs but negative for chick PGCs. Donor and recipient embryos were sexed in 17 pairs which included all four sex combinations. Transferred PGCs, either female-derived ZW type or male-derived ZZ type, were observed in the gonads of both sexes of 15 recipient embryos. The population of donor PGCs ranged from 20 to over 2500. In all four sex combinations, there was a higher population in the left than the right gonad of the embryos.

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The thymus of IQI/Jic mice aged 3 to 15 months was studied chronologically by flow cytometry and immunohistochemistry. Thymic B cells (Thy B) expressing the surface marker B220⁺IgM⁺ were detected in both sexes, but were more prominent in females. Thy B appeared as early as 4 months of age in female mice, and the incidence of Thy B-positive mice and average Thy B ratio in thymocytes increased with age, reaching over 90% and 15%, respectively, after 9 months of age. In males, Thy B-positive animals appeared around 9 months of age and its incidence and average ratio increased gradually to 53% and 5%, respectively, at 15 months. The Thy B-rich thymus was thickened with cortical atrophy and medullary hyperplasia. Small-to medium-sized Thy B crowded and often formed follicle-like structures in the medulla. When mice of various ages were injected with mercuric chloride to induce antinucleolar antibody, many Thy B-rich animals could not develop the antibody, implying that these animals are immunologically impaired. IQI/Jic can be a novel strain to elucidate the relationship between the presence of Thy B and disorders of the immune system.

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In the present paper, we applied analysis of the mandible to a new strain of Japanese White rabbit being developed (Nlb:JWNS), at 5th and 8th generations (F5 and F8), and evaluated the process of establishment, making comparison with the parent colonies (I, K and L), and other established JW colonies (A, E, O and R). The mandibles were measured at 12 sites and the data obtained were calculated by principal component analysis and discriminant analysis. As a result of principal component analysis, the parent colonies were found to be close to one another with intermediate size of the mandible and height of condyloid and angular processes, but in F5 and F8 the mandibles were slightly shorter in height and different from those in the parent colonies. On the other hand, results of discriminant analysis revealed that mandibles were discriminated correctly 100% in colonies A, O and R, and 90% in E and I. Colonies A, O, R, E and I were therefore regarded as established strains. In the developing colonies, the discriminant rate was 70% in F5 and 80% in F8. One mandible from F5 and two from F8 were wrongly classified to the parent colony L, which was the lowest discriminant rate among the colonies examined (61.5%). The results of both statistical analyses suggest that the JWNS are almost established at 8th generation as a new strain.

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This paper describes the effects of goitrogen-induced hypothyroidism on GH, prolactin and the testis size of rats. Hypothyroidism was caused by lifetime-rearing on goitrogen methimazole (MMI). This condition was brought on by adding 0.025% (Weight/Volume) MMI to the mother's drinking water immediately after birth. Offspring, after weaning, were given the same food and drinking water as that of the mother until sacrified. Four experimental groups were designed: group 1, CMF (normal rat chow) and tap water; group 2, CMF with 0.025% thyroid powder and tap water; group 3, CMF and tap water containing 0.025% MMI and group 4, CMF with the thyroid powder and tap water containing 0.025% MMI. The rats were killed at 73 days of age after rearing under the 4 conditions described. Pituitary GH and PRL and serum PRL were significantly less in group 3 than in the others. Testis weight was the same for groups 3 (2.51 ± 0.14 g; Mean ± SD), 1 (2.76 ± 0.07 g) and 2 (2.60 ± 0.06 g). Increased testis weight was noted only in group 4 (3.25 ± 0.1 g). The ratio of testis to body weight was significantly higher in group 3 than in the other groups. The authors concluded that hypothyroidism causes pituitary dysfunction with GH and PRL deficiency and also causes testis enlargement with age.

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In the first experiment, the skin sebum and humidity, perspiration ability of sweat glands, and histology of spontaneous comedones were examined in hairless descendants of Mexican hairless dogs. The skin of females showed lower humidity than that of males. Some animals with a large number of comedones exhibited remarkably high skin sebum scores. The comedones were distributed throughout the dorsal skin, and a cluster of lesions was found mainly in the limbs and prepuces. The sweat glands showed no perspiration in the sudorific test. Histologically, both infant and adult animals had lesions of micro- and/or “blackhead” comedones. Plugged follicles containing abundant keratic substances associated well-developed sebaceous glands. Spontaneous comedones in the skin of hairless dogs were grossly and histologically similar to the acne vulgaris observed in human beings. The skin of some adult animals showed a large number of protrusive comedones which were solid cystic structures containing organized substances. In the second experiment, three kinds of antiacne agents (sulfur and camphor, sulfur and resorcinol, and ibuprofen piconol) were applied daily to the test sites for one month. These antiacne agents caused prominent extrusion of keratin plugs from follicular sites. The results suggest that the hairless dogs are a predictive model for evaluating the efficacy of antiacne agents proposed for acne treatment.

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Fetal thyroid glands of athymic nude mice (BALB/cAnNCrj-nu/nu) were examined morphometrically on day 18 of gestation. Compared to euthymic litter mate controls (BALB/cAnNCrj-nu/+), both the cell height and diameter of thyroid follicles were significantly smaller; fewer well-developed follicles were found in the peripheral region of the thyroid; the body weight and total volume of the thyroid gland were also smaller in nude mice. These results suggest underdevelopment of the fetal thyroid gland of the athymic nude mouse.

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To examine the susceptibility of the epithelial cell line to rat coronavirus (RCV), we inoculated sialodacryoadenitis virus and Parker’s RCV into five cell lines; JTC-19, rat L2, LLC, RCN-9 and LBC cells originating in the lungs, intestines and mammary tumors of rodents. Both RCVs were replicated in LBC and RCN-9 cells, but not in the others. The infectivity titers of both RCVs grown in RCN-9 cells were significantly higher than those in LBC cells in every passage (2.5-3.9 log rate). Both RCVs replicated in LBC cells showed higher tropism to RCN-9 cells than to LBC cells, suggesting that RCN-9 cells are more suitable for the replication of RCVs than LBC cells. The RCN-9 cell line would be useful for the investigation of RCV infection in rodents.

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Tabby (Ta) is a semidominat allele of the locus on the mouse X chromosome, which causes a characteristic coat pattern and developmental defects in endocrinic glands. To establish a method for identifying the X chromosome bearing the Ta allele in early preimplantation embryos, we performed PCR amplification of an X chromosomal microsatellite marker locus from preimplantation embryos obtained from mating between XO female and XY male mice. The microsatellite marker locus was shown to be polymorphic between X chromosomes bearing the Ta and wild-type alleles. The amplification of the marker locus from early preimplantation embryos demonstrated that the Ta locus can be correctly typed by this method from embryos as little as 2 cells.

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To reveal a major cause of postnatal lethality in F₁ Dh/+ male mice from DDD × DH (Dh/+) mating, the current study was performed. Dh/+ males with retarded growth appeared within a few days after birth. The unusual junction between the rectum and the urinary bladder (rectovesical fistula) was found in nine of 22 Dh/+ male mice, and the bladder contained unusual substances derived from the intestines. When the fistula was recognized, the urine was always gelatinous, and the anus was imperforate in eight cases, suggesting that an affected individual would have trouble in urination and evacuation. From these observations we conclude that the rectovesical fistula is a major cause of postnatal death in the F₁ Dh/+ male.

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Cryopreservation of semen from Japanese White rabbits was examined to reduce the number of their males for use in teratological studies. Semen was frozen with liquid nitrogen, preserved, thawed, and tested for motility according to the method of Chen et al. Even after cryopreservation an average of 52% of the thawed sperms were motile. In a previous study, frozen- thawed sperms with a motility of 40% resulted in a high conception rate (approximately 88%) on artificial insemination when New Zealand White rabbits were used [5]. These results indicate the possibility that cryopreservation of semen from Japanese White rabbits may be used in teratological studies to reduce the number of males.

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In order to establish the genetic profiles of three inbred strains of rats (MITB/Yag, MITC/Yag and MITE/Yag; commonly designated as Mitake strains), which were derived from wild specimens of the Rattus norvegicus trapped in Mitake-cho, Gifu, Japan, 63 microsatellite markers were typed in these strains as well as nine other laboratory inbred strains. The data indicate that the MITB and MITC strains are very closely related (3% polymorphism between these strains), whereas the third strain MITE/Yag is relatively different from the other two strains (36% with the MITB, 39% with the MITC). Eighty-three to 58% of polymorphic loci had different alleles between the Mitake strains and the other strains, but 65-35% between the latter strains. In addition, 14 new alleles were found in the Mitake strains. These results suggest that the Mitake strains are useful for linkage analysis.

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