Three kinds of freezing methods were tested with embryos of DNI strain. The survival rate after thawing was 47.5%, 66.7% and 77.8% in the 2-step method, modified slow freezing method and modified 2-step method, respectively. Then, the modified 2-step method was applied to the embryos from 7 strains and a pair of interstrain crosses. PMSG treatment at the beginning of diestrus following HCG treatment after 48 hrs resulted in much yield of 8-16-cell embryos in all strains. The average number for each strain was as follows: DNI; 18.9, DDN; 13.0, BS; 20.4, C57BL/6; 12.9, DBA/2; 17.5, CRN; 19.8, PAN; 13.7 and DNI × C57BL/6-A^y; 21.7. Development of frozen-thawed embryos in culture varied among strains. Proportion of embryos that developed to the morula or blastocyst stage was as follows: DNI; 64.6%, DDN; 71.9%, BS; 53.6%, C57BL/6 ; 57.3%, DBA/2; 65.0%, CRN; 52.5%, PAN; 17.4% and DNI × C57BL/6-A^y; 44.1%. These results indicate that the ability of embryos to survive freezing and thawing is influenced by their genetic background. Live young were produced from DNI, DDN, BS and DNI × C57BL/6-A^y embryos after transfer to recipients. Comparative assessment of the developmental ability of frozen-thawed embryos after transfer among strains should be performed in further study.

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An epizootic of chronic respiratory disease was found in a rat colony. Lungs of the symptomatic rats showed histopathologically severe peribronchial lymphoid cuffing. Filamentous bacteria were detected on the border of the tracheal and bronchial epithelium by light and electron microscopy. These bacteria did not grown on artificial media but propagated in embryonated chicken eggs. The disease was thus diagnosed as cilia-associated respiratory (CAR) bacillus infection. Epizootiological observations of the natural and experimentally induced cases revealed that the disease was highly contagious, slowly progressive and intractable. Contact infection may play a major role in the transmission of this disease.

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Spontaneously occurring calcified lesions were found in the tongues of DBA/2NCrj and CBA/BrA mice. In the DBA/2NCrj strain, the frequency of the lesion was 80% (males) and 88% (females) . The youngest age of a mouse with this lesion was 18 days after birth, and 3-4 lesions were found in the tongue of 6- to 8-week-old mice. In CBA/BrA mice, 20% of females and 48% of males had the lesions. No significant differences were found in the serum calcium concentrations in high and low lesion-developing strains, but the alkaline phosphatase activities in the high-developing DBA/ 2NCrj, DBA/LiA, and CBA/BrA strains were higher than in strains with no calcified lesions.

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The parotid glands of the pika and the volcano rabbit were examined by light and transmission electron microscopy. The acinar cells of the pika consisted of light cells containing basophilic granules of low density, while in the volcano rabbit the acinar cells consisted of light and dark cells containing acidophilic granules of moderate density. Intercalated duct cells were composed of light cells containing a few granules of moderate density. These segments of the two animals were similar in morphology. The striated duct cells in both species were composed of light and dark cells. Most of those in the pika contained a few moderately dense granules. In both animals, no myoepithelial cells were detected around the acini, intercalated ducts or striated ducts, while nerve terminals were observed among the adjacent acinar cells.

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We evaluated a recently developed tail-cuff apparatus containing sensitive photoelectric sensors in the measurement of arterial pressure in rats. A total of 48 male Wistar rats were used in the study. The indirect mean arterial pressure (MPi) was determined from the cuff pressure when the pulse volume oscillations were maximal. To create sufficiently large pulse volume oscillations, we heated the rats for about 12 minutes at 38°C prior to recording the pressure. The heating increased the mean arterial pressure by an average of 4±2 mmHg, as indicated by direct measurement of pressure. Three different sizes of cuffs were tested, with the result that the indirect measurements were nearly identical to those obtained directly when an appropriate cuff size was selected. The MPi was well correlated with the direct measurement of mean arterial pressure before (r=0.918, p<0.001) and during (r=0.903, p<0.001) elevation of arterial pressure via norepinephrine infusion. These results indicate that the MPi determined at maximum pulse volume oscillations coincides fairly well with the true mean arterial pressure.

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Five analbuminemic inbred strains of rats (AD/1, AD/2, AD/3, AD/4, AD/5) were established from Nagase analbuminemic rats (NAR) . They showed no genetic differences in coat color, biochemical marker gene loci and skin grafting test. Their serum levels of total cholesterol, phospholipids, triglycerides, and β-lipoproteins were compared with normal inbred strains (L) derived from Sprague-Dawley rats. Their plasma apoproteins were also examined. All inbred strains of analbuminemic rats showed hyperlipidemia progressing with age although there were slight variations in their lipid and apoprotein levels. These analbuminemic inbred strains of rats may be multigenic models of lipid metabolism abnormality.

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Prolonged prothrombin time in the blood coagulation test was seen in some beagle dogs whose activated partial prothrombin times were distributed within the normal range. This phenomenon suggested possibile abnormalities in coagulation factors II, V, VII, and/or X. Therefore, a revised cross-matching test was given and a determination of coagulation factors related to the extrinsic system was performed. We also determined whether or not factor VII inhibitor was present. The results were as follows: 1) In the revised cross-matching test, the prolonged prothrombin times were revised when normal canine serum was added to the plasma that showed prolongation of prothrombin time, but not when pooled normal canine plasma absorbed with B_aSO₄ was added to it. 2) The level of factor VII in the plasma with prolonged prothrombin time was 5-10% of the level in normal canine plasma. 3) Factor VII inhibitor was not detected in the plasma with prolonged prothrombin time or in normal plasma. Consequently, the prolongation of prothrombin time was attributed to a deficiency in factor VII. This abnormality was confirmed to be congenital.

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Atopic individuals who were exposed to dust in animal rooms for a long time were more likely than non-atopics to have animal-related symptoms. Standard skin prick tests were performed using crude antigens from dander and urine, and 75 to 100% of atopic persons had positive skin reactions. It seems that allergens in animal rooms result from air-borne dust and the dust originates in animal urine and dander. The protein content occurs as dust particles both below and above 10μm in diameter. The dust particles above 10μm cannot pass through face masks, so half of the dust protein is arrested under the mask, but smaller particles pass through. In order to minimize the symptoms, we need to improve the design of cages, animal rooms, experimental rooms, ventilation systems and other protective equipment.

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To investigate the usefulness of spontaneous motor activity (SMA) measurement using the vibrator response method, the acute effects of drugs on SMA were observed in Sprague-Dawley male rats. There were no significant differences between four devices. Methamphetamine (0.3-1 mg/kg, i.p.) and 1-2 mg/kg (s.c.) of apomorphine increased the SMA, but 0.05-0.2 mg/kg (s.c.) of apomorphine decreased the SMA. Apomorphine at 1-2 mg/kg (s.c.) significantly increased the SMA when the vibrator response method was used as compared with the Animex method. These results suggest that the vibrator response apparatus is useful for the measurement of SMA in rats.

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A personal computer system was developed for measuring values of copulatory behavior of small laboratory rodents. This system enabled us to get the analysis data of copulatory behavior of male rats as soon as possible after observation. This present system could be useful to measure other reproductive behavior of small rodents.

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A cylindrical thermistor probe with a rubber disk stopper, which is beneficial for inserting a suppository into the rectum of rabbits without removal of the probe from the rectum, was developed. It is possible to measure body temperature continuously by using this probe in an experiment to assess the effects of a suppository on the body temperature of rabbits. After insertion of a suppository, leakage of the melted suppository from the rectum was not observed. No differences between this thermistor probe and an ordinary thermistor probe in the ability of the probe to detect the febrile response of rabbits injected with a bacterial pyrogen were observed. From these results, it could be concluded that this newly improved cylindrical thermistor probe is suitable for studying the effect of suppositories on the body temperature of rabbits.

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This system for measuring behavioral activity and for its analysis by personal computer as the recording device of the actograph was developed in order to measure the drinking activity and the feeding activity of small laboratory animals. According to the results of the measurement on male DBA/2J mice with this actograph, 84.0% of the drinking activity occurred in the dark period while 16.0% in the light period, and the amount of water drunk by the mouse was about 5.7 ml/day under the conditions of a 12 hour light period and 12 hour dark period. Under the same conditions, 79.6 % of the feeding activity took place in the dark period and 20.4% in the light period. Also there was a positive correlation between both activities.

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