Fifteen male SPF Wistar-Imamichi rats, aged 10, 27 and 44 weeks, that had been raised in the authors' laboratory, were used for the observation of copulatory behavior. Each male was given the opportunity to mate with a proestrous female. During a two hour period, standard measures of copulatory behavior, e. g., mounting, intromission and ejaculation, were documented by a video recording. The following results were obtained; the number of ejaculations in 10-week-old rats, over a two hour period, was 6 to 8. Males showed a subsequent post-ejaculatory interval. The males aged 27 weeks performed 3 to 4 times during the first hour, and then refrained from sexual activity. The copulatory behavior in males aged 44 weeks declined, as compared with that of their 10 and 27 weeks old counterparts.

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Non-tumorous pathological changes in C57BL/6 CrSlc mice, which were reared under a barrier system and died spontaneously, were examined. At 3 months intervals 125 to 209 mice were purchased at 4 weeks of age and raised for the supply of aged animals. A large portion of the mice were used for various experiments between 3 and 30 months of age, while not a small number died spontaneously and were autopsied. The major non-neoplastic lesion was amyloidosis, with incidence of 55.5% and 74.4% for the autopsied female and male, respectively. The organs involved were the liver, kidneys, spleen, adrenal glands, ileum, heart and lungs. Skin ulceration and its scar, cerebral vascular calcification, glomerulosclerosis and sepsis in both sexs, distension of the seminale vesicles in males, fibroblast growth of the adrenal glands in females were commonly found. Incidence of spontaneous neoplastic lesions was 69.7% and 55.1% for the female and male, respectively.

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Incidence of spontaneous tumors in C57BL/6NCrj (CR), C5BL/6 CrSlc (SL) and B6 Crj × DBA/2 NCrj F₁ (BD) mice, which were reared under a barrier system and died natural death, were examined. Cohorts of mice in 200 to 300 each were purchased at 4 weeks of age and raised under SPF conditions. A large portion of the mice were used for various experiments between 3 and 30 months old while not a small number died before use and were autopsied. Median survival periods of the female and male were estimated at 697 and 680 days for CR, 764 and 806 days for SL and 866 and 929 days for BD, respectively. Incidence of spontaneous neoplastic lesions in the autopsied animals were 77.4% and 79.2% of 535 female and 590 male CR, 69.7% and 55.1% of 502 female and 463 male SL, and 75.8% and 78.0% of 298 female and 346 male BD, respectively. In CR, histiocytic sarcoma was the most predominant tumor, accounting for 72.1% of all tumors. In SL, malignant lymphoma was the most prevailing, forming 62.3%, and, in male BD, hepatocellular carcinoma was the most frequent, accounting for 41.8% of all tumors.

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Nineteen hematological and serum biochemical values were analyzed for 91 healthy cats of both sexes (aged 1 to 48 months) that were bred and reared in our laboratory. Age-related changes were found for many parameters. Red blood cell counts (RBC), hemoglobin (Hb), hematocrit (Ht), Mean corpuscular constants, GPT, total protein (TP) and albumin (ALB) initially were low but increased then stabilized. White blood cell counts (WBC), alkaline phosphatase (ALP), inorganic phosphorus (Pi), total bilirubin (TBil), total cholesterol (TC), glucose (GLU), and triglyceride (TG) initially were high, but decreased then stabilized. No agerelated changes were found for GOT, blood urea nitrogen, or calcium. Of the parameters that changed with age, the mean corpuscular constants, GPT, GLU, and TG became stabilized during the first 3 to 4 months of life, but others (RBC, Hb, Ht, TP, ALB) became stabilized after 9 to 11 months, during which period body weight reached a plateau. Some parameters (WBC, ALP, TG, Pi) showed change up to 18 months of age. These results suggest that cats 9 to 11 months old can be regarded as adults ; but for some parameters, cats aged 18 months, or older, are better regarded as adults. Sex-related differences in the values for mean corpuscular volume, mean corpuscular hemoglobin, and WBC that were found after 11 months of age were higher in females. ALB was higher in males.

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Spermatogenesis in the Watase's shrew, Crocidura watasei, was investigated by light and transmission electron microscopy. The cycle of the seminiferous epithelium was divided into 12 stages using the development of spermatids as a main criterion. The steps of spermatids were characterized by morphological changes of the nucleus and acrosomal structure. The relative frequencies of the stages 1 to ×11 were 11.0, 10.3, 6.8, 10.6, 24.0, 6.4, 4.4, 7.9, 6.4, 4.9, 3.7 and 3.6%, respectively. Four types of spermatogonia (A1, A2, In and B) could be discerned by the observation of whole mount samples. The development of spermatids was divided into four phases (Golgi, cap, acrosome and maturation phases), as in other mammals. In Golgi phase of the spermatid, several acrosomal granules were encountered. In cap phase, the acrosome gradually spread over the nuclear surface. In early acrosome phase, the acrosome began to elongate and reached the maximal length in step 8 spermatids. The acrosome of step 8 spermatids was twice as long as that of spermatozoa. In late acrosome phase, the acrosome was on the way of shrinkage. Finally, the fan-shaped acrosome was formed in maturation phase. These findings suggested that the process of acrosomal formation was quite characteristic in the Watase's shrew in that the spermatid acrosome elongated most prominently in the mammals hitherto examined.

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Seventy-one male and 52 female F 344 rats with leukemia used as controls in the 30-month inhalation studies were characterized by hematological and clinicobiochemical findings. Hematological findings revealed that the leukocyte count, mean corpuscular volume, and mean corpuscular hemoglobin increased in both sexes of leukemic rats showing profound anemia, while the platelet count, erythrocyte count, hematocrit, and hemoglobin concentration decreased. In these rats, the serum levels of low density lipoprotein, free cholesterol, total bilirubin, blood urea nitrogen, and triglyceride and the activities of glutamic oxalacetic trans aminase, glutamic pyruvic transaminase, creatine phosphokinase, alkaline phosphatase, and lactate dehydrogenase increased markedly and the level of high density lipoprotein, the oxygen partial pressure, and the cholinesterase activity decreased. Clinical signs such as decrease in redness of the eyes, decrease in body weight, abdominal distension, staining of the public region, and debility were seen in most leukemic animals. These clinical signs and hematological and clinico-biochemical findings may be helpful in diagnosis of leukemia in long-term experiments.

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Specific IgG antibodies were determined by enzyme-linked immunosorbent assay (ELISA) in 7 strains of male and female mice after immunization with ovalbumin. Also, H-2 haplotype and sex-related differences in IgG response to ovalbumin were evaluated using statistical methods, slope ratio assay and parallel line assay. H-2^kstrain mice (C3H/HeN and CBA/JN) showed higher IgG responsiveness to ovalbumin than H-2^d (BALB/cAnN and DBA/2 N) and H-2^b (C57BL/6 N) mice. With regard to the sex-related differences in IgG response to ovalbumin, females in some strains showed higher IgG response than males, but some strains showed no sex-related differences, and sex-related differences in IgG response to ovalbumin did not relate to their H-2 haplotypes. These results may be caused by other immune response genes which control the sex-related immune response than H-2 or other unknown factors.

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In the hamster, guinea pig, rabbit, dog and cat, the right and left atria and ventricles were examined by immunohistochemistry, and the right auricular cardiocytes were studied by transmission electron microscopy. Moreover, ANP-granules in the cardiocytes were analyzed by ultrastructural morphometry. Immunohistochemically, the most intensely ANP-reactive cardiocytes were localized in the right auricle, particularly more prominent in the hamster and guinea pig than in the rabbit, dog and cat. The immunoreaction in the dog and cat was weaker than that in the rabbit. ANP-immunoreactivity was not detected in the ventricular myocardium of any of all species examined, but was occasionally observed in the subendocardium of the ventricular septum. Ultrastructurally, ANP-granules were localized principally in the perinuclear region associated with the Golgi apparatus and scattered throughout the sarcoplasmic layers. The Golgi apparatus of the cardiocytes was better developed in the hamster and guinea pig than in the rabbit, dog and cat. It was poorly-developed in the dog and cat. By ultrastructural morphometry, the number of granules was greatest in the hamster followed by the guinea pig, rabbit and dog or cat, in this order. On the other hand, the diameter of granules was largest in the guinea pig and reduced via the hamster to the rabbit. The diameter was significantly smaller in the dog than in the rabbit. The diameter of granules of the cat was lay between the rabbit and dog.

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Hematological and serum biochemical values of dams and offspring of SpragueDawley rats were measured during late gestation, lactation and postweaning. In dams, slightly low erythrocytic parameters, high platelets and high frequency of neutrophils were seen after parturition although WBC showed no marked changes. On Day 20 of gestation, glucose and triglycerides were extremely high and TP and albumin were low. These changes may be attributed to pregnancy or parturition. In fetuses on Day 20 of gestation and offspring immediately after birth, erythrocytes showed anisocytosis, polychromasia, basophilic stipplings and Howell-Jolly bodies and erythroblasts were found. RBC was low. MCV and MCH were extremely high, compared to adult erythrocyte levels. Hemoglobin and hematocrit slightly decreased before weaning. RBC, hemoglobin and hematocrit increased with age and reached adult levels by Day 56. MCV and MCH values decreased, towards adult levels, until weaning. Platelets rapidly increased and reached adult levels before weaning. WBC increased after birth having higher counts in males than in females on Day 35 and thereafter. Glucose, TP and albumin increased with age and reached adult levels by Day 28. ALP was high in fetuses and changed with age having two peaks similar to those reported in man. Cholesterols gradually increased after birth and had a peak on Day 14. Urea nitrogen, inorganic phosphorus and calcium were slightly high in fetuses and preweaned offspring. Potassium was high in fetuses but no age-related trends were seen in offspring.

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A contamination withMycobacterium scrofulaceumwas experienced in a colony of BALB/c-nu/numice. The contamination was noticed after introduction of C57BL/6 and C57BL/6. Lyt 1. 1 strains into facilities that kept the colony.M. scrofulaceumseemed to be spread by oral infestation and cross-contamination of fecal excretions dung handling of the mice. The organisms were shed continually or intermittently into feces of weanednu/⁺andnu/numice of BALB/c background, and were isolated from the mesenteric lymph nodes and spleen of some of the mice. Some of the bacillus-carrying mice developed serum antibody toM. scrofulaceumof IgG and IgA classes and gave a low degree of hypersensitivity to PPD fromM. tuberculosis.

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The purpose of this study was to examine the effects of solvents, injection sites and embryo age when using chicken embryos for teratological testing. The results obtained were as follows : 1) Solvents : distilled water, physiological saline, sesame oil, 25% ethanol, 0.5% carboxymethylcellulose and 0.1% methylcellulose solution were not toxic in Day-4 embryos (eggs incubated for 4 days) . 2) With 6-aminonicotinamide, air space injection more effectively induced malformations in chicken embryos. With boric acid, however, yolk sac injection was better. It was shown therefore that the appropriate injection site varied according to the test drug. 3) 6-aminonicotinamide induced characteristic malformations when injected into embryos of various ages ranging from4to 13 days of incubation. On the other hand, boric acid was teratogenetic only when injected into Day-3 or Day-4 embryos. It seems, therefore, that the age of the embryo at the time of administration is of critical importance and that the optimum time of administration varies according to the test drug.

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An enzyme-linked immunosorbent assay (ELISA) for serodiagnosis ofBordetella bronchiseptica (B. bronchiseptica) infection in guinea pigs was evaluated. An isolate ofB. bronchisepticafrom lung lesion of a guinea pig was used as antigen after ultrasonication. In the experimental infection, specific pathogen-free guinea pigs inoculated with the bacterium intranasally were examined every 5 or 10 days. The organism was recovered from all animals between 5 and 30 days post-inoculation (p. i.) . Only one animal was sero-positive by agglutination test 30 and 50 days p. i. ; whereas, by ELISA, one animal was positive 5 days p. i., and all the animals showed strong reaction 20 to 50 (end of experiment) days p. i. Field samples obtained from 1983 to 1989 were tested by ELISA. The results corresponded to those of macroscopic observations and bacterial isolation. The ELISA proved to be useful method for detection ofB. bronchisepticainfection in guinea pigs.

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Pregnant rats were irradiated with soft x-ray at a dose of 635 r or 1270 r on Day 9 or 11 of gestation. The eyes of F₁offspring were examined by indirect ophthalmoscopy and slit lamp biomicroscopy in postnatal weeks 3 to 7. Ophthalmoscopic examination of offspring irradiated at a dose of 635r or 1270r on Gestational Day 9 revealed iris and choroidal coloboma together with microphthalmia and anophthalmia at Postnatal Week 3 or later. Choroidal coloboma, an anomaly that cannot be detected by the common external observation method, was found ophthalmoscopically in one rat without any external ocular abnormalities. This fact suggests that ophthalmoscopy in postnatal observation can be useful to detect ocular teratogenic potential of test compounds in preclinical safety studies.

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A congenital diverticulum of the ileum (Meckel's diverticulum), approximately 10 mm long, was detected in a rat and examined histologically. The histological findings were basically the same as in the ileum. Although Meckel's diverticulum is uncommon in the rat, the present report demonstrated the possibility of discovering new cases.

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Two apparatuses were constructed to obtain continuous records of water intake and urinary output in a dog. As a validation of their accuracy, daily patterns of these measurements were observed on a beagle using these two apparatuses during non-treatment and treatment of the diuretic drug, flosemide. During the non-treat-ment, water intakes increased after feeding, but urinary outputs did not show a regular pattern. These patterns were the same as the previously reported patterns. During the treatment, urinary output increased within one hour after treatment. These results show these apparatuses are useful in measuring water intake and uriary output continually on the experimental dog.

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Conventional Syrian hamsters, contaminated with Giardia spp., Spironucleus muris, Trichomonas spp., Pasteurella pneumotropica and Pseudomonas aeruginosa were treated with chemicals in order to obtain specific pathogen free animals. Hamsters kept in the laminar flow rack were treated orally with metronidazole several times to obtain a flagellate-free colony. After all flagellates had been eradicated, one pair of animals were kept in an isolator and mating was allowed to occur. When their offspring reached the age of seven weeks, they were intramuscularly injected daily with netilmicin sulfate for 10 consecutive days. Following these treatments, all of the hamsters were free of Pasteurella and Pseudomonas. Further breeding of these animals was continued in isolators. To cmfirm the absence of selected pathogens, they were placed in a barrier room for further breeding as specific pathogen free animals.

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In Mongolian gerbils, prostatic buds were found in female fetuses at the 23th day of gestation. In the mothers the well-developed prostate gland consisting of a paired lobes was situated on either side of the neck of the bladder.

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Two-cell mouse embryos obtained by in vitro fertilization were transferred into the ampullas of the fallopian tubes of psudopregnant recipients through the wall of the tubes on day 1 of psudopregnancy. A total of 112 embryos were transferred to 7 psudopregnant recipients and 68 young (60.7%) were born.

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This study was undertaken to simplify the preparation procedures for test specimens by applying whole blood collected on filter paper disks. The results of ELISA obtained using specimens collected in this way for the detection of Sendai virus and mouse hepatitis virus antibodies in mice were comparable to those for ordinary ELISA using serum samples.

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The effect of transient cerebral ischemia (from 15 to 180 min) by bilateral carotid arterial occlusion on postischemic mortality rate and the signs of nervous disorder in Fischer 344 rat was studied. Total mortality rate was 40 to 60% during 72 hr of reperfusion following 2 hr ischemia. Postischemic mortality rate did not vary dis-tinctly with 10, 20 and 40 weeks-old.

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