Avoidance, discrimination (right-left) and discriminated avoidance performances of 15 inbred strains of mice were measured on 50 learning trials in each of two daily sessions with a specially designed automated Y-type maze apparatus. Each trial consisted of light and buzzer for five seconds as conditioned stimuli and electric shock for five seconds as an unconditioned stimulus. Intertrial intervals were 30 seconds. The subjects were ten animals of 60-75 days of age for each sex. Highly significant differences among the strains for all the learning performances and negative correlations between the avoidance and discrimination performances of the strains were observed. This suggests that different strains should be chosen for avoidance and for discrimination, when used in behavioral experiments. Among the strains RF/Ms, SWM/Ms and SWR/Ms were superior in avoidance, while C3H/HeMs, DBA/2 and DBAf/Lw were superior in discrimination. C3H/HeMs and C57BL/6HeMs had relatively high abilities for both learning tasks. D103/Ms had the lowest learning ability in avoidance, while SWM/Ms and SWR/Ms had the lowest in discrimination.

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A new hereditary polydactyly (gene symbol Pdn) was found in the course of breeding JCL: ICR mice. The genetic analysis indicated that the polydactyly was an autosomal dominant trait. The homozygotes died within two days after birth. The homozygous fetuses or newborn had 1-3 extra-digits both in the fore- and hindlimbs on the preaxial side. They occasionally showed exencephaly, cleft palate, open eyelid, short tibia and fibula or deformed sternum. The heterozygotes had one extra-digit preaxially in the hindlimb and an enlarged first digit of the forelimb which often showed bifurcated distal phalanx. A tab on the postaxial side of the forelimb was found in all homozygotes and in some heterozygotes.

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A Y-shaped test box was designed for the screening of visual abnormality using negative phototaxis in normal rats. Its availability was determined by examination of 100 animals belonging to non-treated, eyelids-sutured, and eyeballs -enucleated groups. Two kinds of examination were undertaken, the first being observation of the general behavior of the animals in the box for one minute. The second was 4 trials at selection of the dark area of the box given to each animal. In each examination many animals could be tested in a short time. The behabioral pattern of the eyelids-sutured and the eyeballs-enucleated groups was significantly different from that of the non-treated group. The selection rate for darkness by non-treated, eyelids-sutured, and eyeballs-enucleated groups in the second examination was 97.5, 84.5, and 50.0 percent, respectively. Therefore, successful estimation could be possible by both procedures and it was possible to numerize the gained value and analyze statistically in the second examination. It was concluded that this simplified method for testing visual function should prove very useful as a behavioral teratology screening test in routine reproduction studies.

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In order to determine the appropriate age for the water filled multiple T-maze test, Wistar-Imamichi strain rats (SPF) 3 to 10 weeks of age were given daily 3 repeat trials on three consecutive days. Learning ability was evaluated on the basis of daily decrease of errors in the water maze test. Elapsed time to reach the goal, errors and variations of these decreased with progressing trials regardless of age and sex. Comparing to the rats under 4 weeks of age, errors in the 3 rd day trials became constant at lower level in rats over 5 weeks of age. These results suggest that the learning ability of rat may reach adulthood by 5 weeks of age. Brain weight also attained a plateau at 4-5 weeks of age in both sexes of rats.

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Pathogenic agents were isolated from affected salivary glands of rats with sialodacryoadenitis (SDA) by means of intracerebral inoculation to newborn mice and inoculation to primary rat kidney cell cultures. The properties of these isolates, irrespective of the isolation techniques, were in general agreement with that of SDA virus strain 681, and they were identified as SDA virus. In addition to the known properties, following characteristics were noticed: (1) Particles of SDA virus bore two different long and short surface projections. (2) Some antigenic differences were observed between the present isolate 930-10 and the strain 681. (3) It was suggested that SDA virus grew better at 35°C than at 31°C, 33°C, 37°C or 39°C. (4) SDA virus did not propagate in DBT cells.

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Pathological observations were carried out on 100 male rats of Sprague-Dawley strain obtained from 5 outbreaks of sialodacryoadenitis (SDA) . In accordance with clinical and macroscopic findings, principal microscopic changes were found in the salivary (submaxillary and parotid) and Harderian glands. Lesions observed in these different glands were essentially similar to each other, and characterized by degenerative changes in the epithelial cells of the ducts and acini associated with marked and extensive serous inflammation in the interstice. Furthermore, squamous metaplasia of the ductal epithelia was a common feature to these glands in the late stage of the disease. Some differences, however, were detected between the changes of the salivary glands and those of the Harderian glands. Firstly, the ductal epithelial cells were affected at first and the acinous epithelial cells were damaged only secondarily in the active inflammatory process in the salivary glands, while both ductal and acinous epithelial cells were involved equally in the primary lesion in the Harderian glands. Secondly, the increase in connective tissue elements in the reparatory process was extremely marked in the Harderian glands as compared with the salivary glands. Consequently, in the lesion of Harderian glands in the late stage, original construction was almost indiscernible, and the ducts and acini were only recognized as disseminated islets in actively proliferated connective tissue elements.

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[in Japanese]

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Using the RaBA-Super System (Rapid Blood Analyzer System), the clinical values for chemical constituents of blood in Shiba goats bred in Stock Farm, University of Tokyo, were determined on the following items: total protein, albumin, TTT, glucose, BUN, total bilirubin, total cholesterol, triglyceride, GOT, GPT, ALP, LDH, CPK, cholinesterase, calcium, and inorganic phosphorus. The results obtained were summarized as follows: 1) All items determined were to be analyzed by means of the RaBA-Super System, although the values for total bilirubin, total cholesterol, TTT, ALP and CPK varied considerably with individuals. 2) The values of adult female goats were significantly higher than those of young ones in total protein and albumin, and lower in glucose, cholinesterase, ALP and CPK. 3) The values for GPT and BUN of adult female goats in summer were significantly lower than those in winter and autumn. 4) The values for triglyceride and albumin of adult female goats using the RaBA-Super System were inconsistant with those analyzed simultaneously by the manual method, but a significant linear correlation was recognized between the both methods.

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The Ossa cranii and Ossa trunci in Lepus brachyurus brachyurus, Pentalagus furnessi and Oryctolagus cuniculus (strain: JW-NIBS) were investigated morphologically and osteometrically. The number of coccygeal vertebrae is 10-12 in Lepus, 10-11 in Pentalagus and 15-17 in JW-NIBS. The number of upper cheek teeth of Pentalagus is six on one side. Therefore, Lyon's view that the number of upper cheek teeth of Pentalagus is five may not be applicable to use as one of the discriminative characteristics. The sizes of orbit and tympanic bullae in Pentalagus are remarkably small. The length of neurocranium and the inner breadth of caudal surface of vertebral foramina in cervical, thoracic and lumber vertebrae in JW-NIBS are smaller than those in Lepus and Pentalagus. Among three genera, there are conspicuous differences in shapes of spinous and transverse processus in the lumber vertebrae. The coefficient of variability of the measurements in JW-NIBS is smaller than that in Lepus.

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Eradication of Sendai virus from an infected mouse breeding colony was successfully made by sacrificing all offspring younger than 5 weeks of age at a time and then newborns as well as severely affected breeder mice for successive 2 weeks. By this method, number of breeders decreased to two third of those in the original colony but recovered again about 2 months later.

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An automatic watering device was developed for the pika (Ochotona rufescens rufescens), using drinking nozzles for rat use and plastic pipes. This device was used for at least one year without any mechanical troubles, resulting in labor saving of animal caretakers. No difference in growth was observed between pikas reared with the automatic watering device and those maintained with conventional watering bottles.

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