[in Japanese]

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The TG strain of sialodacryoadenitis (SDA) virus propagated in LBC cell culture (TGr/LBC) reacted strongly with anti-TGr rat serum in complement fixation (CF) tests, showing much higher titers with anti-TGr rat serum than mouse hepatitis virus MHV-NuU antigen. The antigenicity was not affected after ether treatment while infectivity was lost. The TGr/LBC antigen might be useful in seromonitoring for SDA infection in rats.

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Mated female mice of the NCS strain, aged 90 (control group), 180, 210, 240, 270, 300, 330, 360 and 420 days old, were studied for pre-and post-implantation loss of embryos. The percentage of pre-implantation loss in mice aged 90 to 210 days was 1.7/11.8 (14.4%) to 2.7/11.7 (23.1%) . In mice aged 240 to 300 days it increased significantly as compared to the controls (46.5-90.2% versus 14.4%) . It reached 100% in 300-days-old mice. The post-implantation loss of embryos and/or fetuses in mice aged 90 to 240 days was 1.0/10.2 (9.8%) to 2.5/9.0 (27.8%) . In mice aged 270 to 300 days it increased significantly compared to the controls (100% versus 9.8%) . The decrease in reproductive activity appeared first in a decrease in litter size, followed by a decrease in the number of blastocyst and implantation sites, and finally by anovulation during the process of aging in NCS mice.

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During pseudopregnacy (PSP) two surges of prolactin (PRL) secretion from the pituitary are observed, the nocturnal surge at dawn and the diurnal surge in the evening. An attempt was made to clarify the correlation between changes in serum and pituitary PRL concentrations on day 5-6 of PSP. During the nocturnal surge, pituitary PRL concentration decreased significantly from 0000 hr to 0300-0600 hr. On the other hand, the high pituitary PRL concentration remained unchanged during the diurnal surge from 1200 hr to 1800 hr. These findings suggest that the nocturnal and diurnal PRL surges are regulated by separate controlling mechanisms.

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DBA/2FG-pcy and C57BL/6FG-pcy congenic strains were established by transferring the polycystic kidney disease gene, pcy, to DBA/2 and C57BL/6 mice. We carried out pathological and hematological examinations of these strains at 4, 8, 16 and 30 weeks of age. In DBA/2FG-pcy mice more than 8 weeks of age, macroscopic renal cysts were observed on the surface of both kidneys. Their kidneys weight was significantly greater than in DBA/2 mice at all ages examined. Microscopic renal cysts were evenly distributed at 4, 8 and 16 weeks of age. At 30 weeks of age, the kidneys were filled with numerous polycysts. In C57BL/6FG-pcy mice, no macroscopic renal cysts were found until the animals were 30 weeks old, and the weight of their kidneys was greater than in B 6 mice of the same age. From 8 weeks of age on, a limited number of mioroscopic renal cysts was observed, and many renal cysts were found adjacent to the enlarged Bowman's capsules. With age, the red blood cell count and hematocrit level decreased while the platelet count increased in both strains, with greater changes occurring in DBA/2FG-pcy mice than in C57 BL/6FG-pcy mice. These findings demonstrate that polycystic kidney disease exhibits strain differences in animals with a DBA/2 and C57BL/6 background. Our results suggest that phenotypic expression of the pcy gene in the mouse depends on genetic background, and that variations in the severity of human polycystic kidney disease may be explained, at least in part, by individual differences in genetic background.

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The major obstacle to clinical application of artificial blood vessel grafts with inside diameter of less than 4mm is neogenic intimal hypertrophy at anastomotic sites. With the aim of preventing this artificial blood vessel graft anatomotic intimal hypertrophy, attempts have been made to improve surgical techniques and develop new materials for sutures and the grafts themselves. In the assessment of the preventive effects of various measures on anastomotic intimal hypertrophy, it is desirable to minimize variation in preoperative arteriosclerotic changes and uniform hemodynamics after vessel replacement surgery among the subjects. The present authors succeeded in creating an infrarenal abdominal aorta replacement model that meets these requirements using rabbits, and conducted experiments using this model to assess the effects of hyperlipidemia on anastomotic intimal hypertrophy. The anastomotic intimal hypertrophy lesion in the present rabbit infrarenal abdominal aorta replacement model is both morphologically and his-tologically similar to that found in human artifical blood vessel graft anastomotic sites. In addition, this model permits the easy obtainment of animas showing the same hemodynamic status after vascular surgery. For these reasons, the present model is expected to serve well as an experimental model of artificial blood vessel graft anastomotic intimal hypertrophy.

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To produce an experimental model of diabetes in animals, ICR mice were inbred until the 20th generation by two-way selection toward the high-and low-incidences of alloxan-induced diabetes. Changes in successive generations in the incidence of such diabetes, in blood glucose levels, growth patterns and reproductive performance were studied. The incidence of alloxan-induced diabetes was 41.1% in the basal population ; in the high-incidence strain, it was 98.7% in F13, ranging between 90 and 99% in later generations ; and in the low-incidence strain, it reached 0 % in F 7, remaining near that level in later generations. The heritability of the incidence of alloxan-induced diabetes determined at the beginning of selection was 50-60%. The blood glucose level was 251 ± 19mg/dl in the basal population ; in the highincidence strain, it was 423±11mg/dl in F13, ranging thereafter between 340 and 455 mg/dl ; and in the low-incidence strain, it was 128±4mg/dl in F7, then varying from 120 to 140mg/dl in following generations. The heritability of the blood glucose level determined at the beginning of selection was 40-60%. No marked decrease in growth or reproductive performance accompanied successive selections. Successive generations of the high-incidence mice, however, tended to become heavier than the lowincidence animals. The high-and low-incidence strains, established in the 20 th generation, were named the ALS (alloxan-induced diabetes-susceptible) and ALR (alloxan-induced diabetes-resistant) strains, respectively.

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The skin and lymphoid organs of Mexican hairless dogs and their hairless offspring were examined histologically. The hairless dogs lacked most hairs except for sparse hairs on the head, tail and feet. The skin of newborn pups consisted of a thick epidermis with epidermal ingrowths forming the rudiments of hair follicles. In older dogs more than 2 months of age, however, the epidermis was thin and the ingrowths were few. Neither hair follicles nor skin glands were present. The hairy skin of the head and tail had hair follicles with sebaceous glands. Regarding the lymphoid organs, the newborn pups possessed a thymus like haired pups. But in the older dogs more than 2 months of age, the thymus was atrophied and the lymphocyte population was too sparse to demarcate the cortex and the medulla. Lymphocyte accumulation in older dogs was also poor in the spleen and mesenteric lymph nodes. The present findings indicate that the hairlessness of the Mexican hairless dogs and their descendants is accompanied by early atrophy of the thymus after birth, and is followed by poor accumulation of lymphocytes in the thymusdependent area of the spleen and the mesenteric lymph nodes. The defect of the thymus in the hairless dog seems to be different from that in athymic nude mice and rats. Further studies are needed to elucidate the immunological response and function in hairless dogs.

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In pseudopregnancy of the rat prolactin (PRL) is released in the form of twice daily surges (nocturnal and diurnal surges) . An attempt was made to examine the effects of urethane anesthesia on PRL surges during pseudopregnancy of the rat. In a preliminary study, using the continuous blood sampling method, the nocturnal PRL surge was completely blocked when urethane (l.Og/kg BW) was administered at 0: 00 hr. Urethane (1.Og/kg BW) was injected at0: 00 or 12: 00 hr, and serum and pituitary PRL concentrations were measured at 6: 00 or 18: 00 hr, respectively, to study the effects of urethane on nocturnal or diurnal PRL surges. There were no serum PRL surges during either the nocturnal or diurnal periods following urethane injection. The experiment examining pituitary PRL concentration at 6 : 00 or 18 : 00 hr confirmed that urethane (1.Og/kg) anesthesia suppressed the release of PRL surge from the pituitary.

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Adult female rats showed increase in ambulatory activity and marked decrease in drinking behavior at early dark period (18: 00-24: 00) of proestrus stage before ovulation. In this study, we observed the changes in patterns of ambulatory and drinking activities of immature rats associated with estrous cycle during growing period. Immature female rats of the Wistar-Imamichi strain were used, and both behavioral activities were measured continuously, using Gundai type Ambulodrinkometer. From these observations, it was found that the typical patterns of ambulatory and drinking activities which were observed in adult female rats appeared at the sixth (51-60 days old) and the third (39-49 days old) estrous cycle, respectively.

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The achromatic epithelial cells (AEC), whose cellular materials remain unstained by several stains, e. g., H·E, PAS, Alcian blue, Orange G Anilin blue and Mucicarmin, are detected in the intestinal mucous epithelium of the Iar : Wistar Imamichi rat from the 19th day of gestation to the 21st day after birth. The results of light microscopic and transmission electron microscopic observations suggest that the rats AEC are equivalent to the previously reported vacuolar cells (VC) in cattle and in mice. The present paper describes that rat intestinal AEC appear first in the small intestine, and spread progressively toward the anal direction, while they disappear first in the cecum, and finally disappear at the ileum and the colon 22 days after birth.

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The effects of anti-rheumatic drugs (lobenzarit (CCA) ; 10 and 50mg/kg, cyclophosphamide (CP) ; 5mg/kg and dexamethasone (DM) ; 0.25mg/kg) were evaluated immunologically and histopathologically on DBA/1J mice that develop polyarthritis after immunization by the intradermal injection of type II collagen. Serum anti-type II collagen IgG levels in the groups treated with CP and DM were significantly suppressed to 1/2 and 1/10 as compared to those of the positive control group, respectively. Those of both groups treated with CCA were not different from those of the positive control group. Histopathological examination revealed that treatment with CP and DM markedly reduced or suppressed inflammatory changes and resulted in low incidence of arthritis. From the standpoint mentioned above, treatment with anti-rhematic drugs suppressed the development of arthritis in this model, and we could confirmthat this model was useful for evaluation of the effect of anti-rheumatic drugs.

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The copulatory behavior in sexually inexperienced male voles aged 9-13 weeks old was observed under dim red illumination. Proestrous females were used as stimulus voles in copulatory behavior tests. A 30-min test session was recorded. All males showed at least one ejaculation within 30 min. In addition, the pattern of copulatory behavior in male voles was compared to that reported previously in male hamsters. The frequencies of mount, intromission and ejaculation in male voles were similar to that in male hamsters but there were significant differences in the latencies of mounting, intromission, ejaculation and postejaculation between the two species.

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To know the conditions of contamination by the chemicals in the experimental animal diets, the contents of nitrosodimethylamine (NDMA) were analyzed in the diets for mice and rats. The raw materials of the diets were also analyzed. In addision, NDMA levels were determined in the diets which were stored long or heated in the autoclaves. The averages of NDMA in these diets were less than 10 ppb. In the raw materials, alfalfa contained a higher levels of NDMA. There was no clear tendency of increase or decrease in NDMA levels, when the diets were stored for six months at room temperature (23-25°C) or at low temperature (7-10°C) . Heating the diets at 121°C, no remarkable changes were observed in NDMA levels. It seems that little adverse influences on the conduct of the animal experiments would be anticipated by the NDMA in the commercial diets.

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X-ray photographs were used to analyze auto-watering nozzles for structural defects. Defects were observed in 58% of the nozzles by a water pressure test, and in the majority of these, X-ray films showed that the combined length of the core section spring and packing (L) was greater than 1.81cm, and the spring (S) was Yshaped. Among those nozzles for which the water pressure test demonstrated no defects, (L) was less than 1.80cm and (S) was in the form of an isosceles triangle. Accordingly, it became evident that there is a close relationship between water leakage and defects in the internal strcuture and that it is possible to assess the quality of auto-watering nozzles by X-ray photography.

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It is well known that the male rats paired with receptive females emit the 22-kHz vocalization after ejaculation. The question addressed is whether after ejaculation injected with PCA without receptive females the 22-kHz call would be emitted. Emission of the 22-kHz call in males injected by PCA was not observed after ejaculation.

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The staining characteristics of the peripheral blood cells from mouse, rat, guinea pig, rabbit, dog, marmoset and monkey were studied. In marmoset, it is easy to distinguish neutrophils from eosinophils by using the phosphate-buffered solution of pH 5 or 6. It was found in the special staining methods that neutrophil granules showed intense peroxidase and Sudan black B reactions in marmoset in comparison with those in the other species of experimental animals. Neutrophil granulesin rabbit was, however, intensely stained with esterase and acid phosphatase.

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A survey on the number of animals used in experiments including bioassay, diagnosis, education and preparation of biological agents such as vaccine between April 1989 and March 1990 was conducted. Out of 823universities, insitutes, testing laboratories and companies, 574replies were received. The distribution of the number of animals is shown in the following tables:

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