An outbreak of dermatophytosis by Trichophyton mentagrophytes infection was observed in a breeding stock of the Wistar-Imamichi rat. Typical cutaneous lesions such as alopecia and hyperkeratosis due to the fungus were observed in 10% and 44% of adult females, and males respectively. No infection was seen in infant, even in those fostered by infected females. By 3 repeated cultivations of the hair, T. mentagrophytes was isolated from 107 (90.7%) of 118 rats clinically diagnosed as dermatophytosis. In order to maintain the original stock, the usual wholesale slaughter program was avoided and the following control measures were takers. After sacrificing all rats with the cutaneous lesions, the breeding colony was transferred temporarily to a separate animal room. The resulting vacant room was then disinfected 3 times with 10 % formalin, followed by spraying with 3 % sodium propionate solution 3 month later. The progenies from the non-infected mothers were dipped into 3 % sodium propionate solution and transferred back into the disinfected animal room for re-colonization. Frequent sterilization of all equipments with iodophor, balsam and formalin was carried out. The room sterilized monthly with iodophor and 70 % alcohol. Daily observation of all rats and monthly screening by culture test was done thereafter. As a result, no infection has been detected 4 month after recolonization, except for the 3 rats which were sacrificed immediately after detection. On the basis of the culture test and clinical observation, no infection was observed in the treated rat colony for the next five following years. Therefore, the effectiveness of these procedures of the eradication of T. mentagrophytes infection from a rat colony was shown to be quite reliable.

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Mice with a strange coat color were found in the KSB strain and separated as KSB-fe after fixation for this gene. These mutant mice have faded coat color (black becomes gray), with white underf ur, the pigment chaning towards white accompanied by frequent skin lesions. Faded homozygotes show a loss of pigment granules with ageing. Genetic studies were conducted with mice bearing this faded coat color. The mode of inherit-ance of the faded coat color was established to be autosomal recessive and the name faded (fe) was proposed. Faded was not allelic to dilute (d), leadend (ln), beige (bg) or pink-eyed dilution (p) loci.

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Age-related and strain-specific patterns of various hematological values, differential counts of white blood cells, total serum protein concentrations and protein fractional values in ICR/d-strain rats were compared with those of two control strains, Jcl: Wistar and Jcl: SD rats from the 4th to 24th week of age, to study the factors related to chronic dermatitis. Determinations of hematological values and white blood cell differential counts revealed a definite tendency toward leukocytosis, relative neutrophilia and eosinophilia, significantly higher neutrophils/lymphocytes ratios and significant thrombocytopenia, all of which progressed with age. Levels of total protein concentrations tended to be slightly lower than those of the two control strains at most ages, but the difference was significant only between the ICR/d and Jcl : SD rats. Fractional values of gamma-and beta-globulins showed relatively higher levels, both of which persistently increased with age and in approximately inverse correlation with the changes in the fractional values of albumin. Fractional values of alphas-globulin showed markedly lower levels than those of both control strains at all ages. In conclusion, ICR/d-strain rats have definite constitutional abnormalities possibly playing some role in the occurrence and progression of chronic dermatitis of the“atopic”type.

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The seminal vesicle epithelium of the mouse and golden hamster was examined by light microscopy and by transmission and scanning electron microscopy. By transmission electron microscopy, in the seminal vesicle epithelium of both animals secretory epithelial cells which consisted of mostly light and a few dark cells were observed. The epithelial cells possessed secretory granules which contained a densely stained core. The secretory granules in the mouse epithelium reacted weakly with periodic acid-Schiff (PAS) stain and were slightly stained with alcian blue (AB), and those in the golden hamster exhibited strongly positive reactions with PAS and AB. The nuclei in the mouse tissue were spherical or ovoid, and those in the golden hamster tissue had a few lobes. By scanning electron microscopy, the apical surfaces of most of the epithelial cells were commonly flat or domed, and those of some epithelial cells protruded into the lumen as apocrine-like processes, or possessed small and large orifices. Besides the epithelial cells, there were cells characterized by pseudopodium-like cytoplasmic projections, a few membranous structures, an irregular nucleus, and cytoplasm containing a few dense bodies, in the basal portions of the epithelial cells, or between the basal lamina and the epithelial cells. These cells of the two species were similar in their features.

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In order to clarify the role of immunity on the development of dermatitis in NC mice, the following experiments were carried out. In neonatal thymectomized NC, thymic reconstituted NC-nu/nu, and passively serum transfered NC-nu/nu mice, incidence of the dermatitis was examined. Immune response to sheep red blood cells (SRBC) and number of Thy-1 positive cells in mesentric lymph node were used as indicators of the cell mediated immunity. Although antibody to SRBC and the number of Thy-1 positive cells in neonatal thymectomized NC mice were greatly reduced, development of the dermatitis in these mice was not suppressed at all. On the contrary, thymic reconstituted NC-nu/nu mice which recovered immun response to SRBC and number of Thy-1 positive cells to the normal levels did not develop the dermatitis. Passive transfer of the serum obtained from NC mice which developed severe dermatitis, could not induce the dermatitis in NC-nu/nu mice. These results suggest that the dermatitis in NC mice is not mediated by immune mechanisms but by other complexed factors. The absence of the dermatitis in NC-nu/nu mice may be due to nu gene effects other than those of immune defect.

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The age-related changes in the number of follicles classified according to size were investigated. The number of large follicles expected to ovulate spontaneously was not influenced by age, though the number of small follicles 250-549μm in diameter, recovered by PMSG and hCG, was not constant. There was no relationship between the number of large follicles and small ones. This study suggests that the variation in ovum count after superovulation depending on age may be based on the variation in the number of small follicles.

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The incidence of spontaneously occurring ventricular septal defects (VSD) in PIKA neonates and its fate during development are investigated. A total of 160 PIKAs were used in the present study. They consisted of three groups; first, 56 live neonates, second, 37 3-week-old live animals and third, 68 animals which had died during the first two weeks after birth from unknown causes. As high as 8.9% (5 cases out of 56) of the live neonates revealed isolated ventricular septal defects of membranous type. Decreased incidence (2.7%) was seen in 3-week-old PIKAs. Its implication and significance are evaluated in the discussion.

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A black coat-color mutant with tremor was discovered in babies of 61 generations of an inbred strain APG of Syrian hamster which had been maintained in the Nippon Institute for Biological Science, Laboratory Animal Research Station. The genetical analysis by matings between four inbred strains which had different genes in the E and B loci and four mutant strains which were introduced the mutant gene into the four inbred strains and characterization were carried out on the mutant. The results obtained are summarized as follows: 1) The mutation occurred in a different locus with E and B loci. 2) The mutant was controlled by an autosomal recessive gene designated as“bt”, and it was thought that both tremor and black coat-color were the pleiotropic effect of bt gene. 3) At least one E gene in the E locus was necessary for the appearance of black coat color. Therefore, the coat-color remained cream in ee (cream) hamsters showing only trembling. 4) The degree of blackness of the coat-color of EE hamsters differed from Ee ones. The former was darker than the latter. 5) The mutant may be a useful animal model for studying abnormal myelogenesis and biosynthesis of melanin.

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The thermistor probe for estimating the effects of an antipyretic suppository after its administration into the rectum of the rabbit was studied. A thermistor probe with three rubber disk stoppers was confirmed to be able to prevent the leakage of drugs from the rectum of a rabbit restrained in a neck stock. By using this newly devised thermistor probe or the usual thermistor probe without a stopper, the febrile response was determined in rabbits injected with bacterial pyrogen. There was no difference in the ability to detect rectal temperature between the two thermistor probes. From these results, it could be concluded that this newly devised thermistor prove was useful in studying the effects of antipyretic suppositories in rabbits.

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According to the Aschoff's role, exposure to continuous light (LL) results in the elongation of the free-running period of the rat circadian rhythm. However, the LL may not always mean the constant intensity of the light for the suprachiasmatic nucleus, since the rat may regulate the contrast of the illumination by their eyelids which are closed during the sleep phase. In this study, the surgical removal of the eyelids under the LL caused arrhythmicity of the locomotor activity in 7 of 10 rats. The remaining 3 rats maintained the free-running rhythm after the removal of the eyelids. These results suggest that constant light may affect the free-running rhythm of the rat with or without eyelids in the different manner.

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Indirect fluorescent antibody method was applied for a detection of lymphocytic choriomeningitis virus (LCMV) antibody in colonies of laboratory animals in Japan. The results showed that the antibody exist in SPF mice (3/152, 2.2%) and conventional mice (30/539, 5.6%) with the titers ranging from 1: 10 to 1: 160. The antibody was also detected in 2.2% (2/89) of Syrian hamsters, and 2.9% (2/68) of Apodemus agrarius, 21.4% (3/14) of Japanese harvest mice which have been maintained as laboratory colony for several years. However, the antibody was not demonstrated in Mongolian gerbils, Suncus murinus, guinea pigs and rats, thus far. These results indicate that LCMV infection is present in laboratory animals in Japan, and pointed out the importance of microbiological monitoring for LCMV.

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The anterior part of the eye was examined with 1, 531 newborn cynomolgus monkeys (Macaca fascicularis) . A male (about 0.07%) of those newborns was noticed to have white opacities in his both eyes (Fig. 1) . This finding was diagnosed to be bilateral congenital cataract by observing with a slit-lamp biomicroscope. Partial resorption of the white opaque part occurred one week after birth in the right eye (Fig. 2) and three weeks after birth in the left eye (Fig. 3) . As a result of the resorption, observation of the ocular f undus by an ophthalmoscope became possible at two and seven weeks of age in the right and left eyes, respectively (Figs. 6 and 7), even though the ophthalmoscopic figures were not complete. White opacities occupied again nearly the whole area of the lens at 10 months of age in the left eye (Fig. 4) and at 14 months of age in the right eye (Fig. 5) . Breeding studies are needed to determine if this case has any genetic background.

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To prevent the bacterial contamination of the drinking water, we developed a periodical draining machine system which were composed of the electromagnetic valve and the time switch. The machine system is able to replace standing water with fresh water on optional volumes and intervals. The total bacterial numbers of standing water were counted as an indicator of the bacterial contamination. The number of total bacteria were reduced to less than 5 per ml by working the machine system on 6-hour-interval with replacing twice as much as standing water, although more than 10³ per ml of the bacteria were found when the system was not operated. It was demonstrated that the periodical draining of the machine prevented the drinking water in auto-watering piping from bacterial contamination.

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Two inbred rabbit strains, JWY-NIBS and NWY-NIBS, were established by full-sib mating in the Nippon Institute for Biological Science, Laboratory Animal Research Station. The origin, breeding history, and biological characteristics of the two inbred strains are as follows. 1. JWY-NIBS: Origin: Japanese white rabbits which had been originally kept at a farm near mount Takao, then transferred to another farm in Fuchu and maintained as a closed colony for a long time. Date of the first full-sib mating: April, 1964. Date of the 20th full-sib mating: June, 1981. Age of maturity: 7-month-old in females, 7.5-month-old in males. Body weight at maturity: 2.8-3.0 kg in females, 2.8-2.9 kg in males. Marker genes: Hemopexin; Hx^s. Esterase; Est-1^s. α-Protein; F type. 2. NWY-NIBS: Origin: A strain III of Newzealand white rabbits imported from the Jakson Laboratory in USA. Date of the first full-sib mating: November, 1967. Data of the 20th full-sib mating: July, 1982. Age of maturity: 7.5-month-old in females, 8-month-old in males. Body weight at maturity: 2.8-3.0 kg in females, 2.9-3.1 kg in males. Marker genes: Homopexin; Hx^F. Esterase; Est-1^S. Est-2^f., α-Protein; S type.

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