Reproductivities of mother mice of inbred strains were investigated and a project for their efficient production was made on the basis of the data of reproductivity. Inbred strains of mice used were C3HeB/FeJax, C3H/HeMs, C57BL/6Jax, CBA, BALB/cHe, A, Rill and DBA/2, which were maintained by sister x brother mating in our laboratory. After 70 days of age, each female was mated with a male and concurrent pregnancy was planned until the 3rd lactation. Interval between litters was approximately 4 weeks in all strains except BALB/cHe, of which interval was about 5 weeks (Fig. 1) . There was marked difference in litter size among strains; the largest was 6.4 in C3HeB/FeJax and C3H/HeMs and the smallest was 4.2 in DBA/2 (Fig. 2) . Normal parturition ratio was better in C3HeB/FeJax, C3H/HeMs, CBA, C57BL/6Jax and A than in BALB/cHe, RIII and DBA/2 (Fig. 3) . The rearing ratio on day 20 of lactation was lower in RIII, DBA/2 and A than in the other strains (Fig. 4) . As shown in Table 2, strains with larger mothers had a trend to produce larger pups than strains with smaller mothers, while there was no large differences among strains in the pups' growth ratio. From the data shown in Tables 1 and 2 and Figs. 1-4, it would be considered that the reproductivity was better in order of C3HeB/FeJax, C3H/HeMs.......DBA/2. The results of interval between litters indicate that numbers of groups starting mating are 5 and 4 in BALB/cHe and in the other strains, respectively, to produce weanling pups every week (Fig. 5) . Number of parents required per group is obtained by the following formula;
Number of weanling pups to be produced/Rearing ratio on day 20×litter size × normal parturition ratio
and number of cages required is to be obtained by multiplying mumber of parents per group with number of groups. For example, number of parents or cages required in each strain for production of 100 weanling pups a week is presented in Table 3. Number of cages was the smallest in C3HeB/FeJax (76) and the largest in DBA/2 (200) which is to need more cages than twice of those of C3HeB/FeJax. The order of number of parents or cages necessary for production of 100 weanling pups a week was in accord with the order of reproductivity.

View full abstract

Two groups (A and B) of Sprague-Dawley-JCL rats, obtained from a commercial breeder, were used for the spontaneous tumor incidence study. Group A consisted of untreated 108 males (mean life-span; 670 days) and 128 females (mean life-span; 701 days), and Group B consisted of 21 parous and 20 non-parous females, which were sacrificed at 730 days of age. In group A pituitary adenoma was found in 20.3% of males and 46.9% of females, and mammary tumor in 62.5% of females (fibroadenoma 92% and adenocarcinoma 8%) . The two females with adenocarcinoma showed a lung metastasis. Seventy-eight % of animals with pituitary adenoma had also mammary tumor. Parathyroid tumor associated with renal disease was always found in 20.3% of males and 9.0% of females, showing histological findings indicative of secondary hyperplasia. In addition, spontaneous tumors were found in the adrenals (4 males and 2 females), thyroids (2 males and 2 females), ovary (1 female), liver (1 male), kidneys (1 female), seminal vesicles (1 male), and lungs (1 male) . In group B, tumors were found in the mammary glands (10 parous and 15 non-parous females), pituitary (5 and 9), adrenals (3 and 4), ovaries (1 and 1), and uterus (6 and 1) . From the above results, spontaneous tumor incidence in the Sprague-Dawley-JCL rats are concluded to be relatively high particularly in the pituitary and mammary glands, and sex and parous-nonparous differences were recognized. In addition, many rats had both pituitary and mammasry tumors and tumors in other endocrinous glands were also observed in some animals. Aging and endocrinologic changes may play an important role in the incidence of spontaneous tumors.

View full abstract

The number of ova and the time of ovulation in Donryu, Sprague-Dawley and Wistar rats as well as the time required to accomplish the ovulation in Sprague-Dawley rats in three different lighting conditions were determined. The 90-120 day-old animals having shown at least seven consecutive estrus cycles of 4-day length were sacrificed on the day of estrus.
The mean number of ova were 12.6±2.0 in Donryu, 13.9±2.0 in Sprague-Dawley and 13.7±1.7 in Wistar rats. Onset of the ovulation under lighting daily from 06: 00 to 18: 00 (LD12: 12) . occurred at 02: 10 in Donryu, 01: 34 in sprague-Dawley and 01: 54 in Wistar. Time required from the onset to ending of ovulation in the above three strains were 3h 38min, 4h 23mm and 3h 50min, respectively, and most animals completed the ovulation before the following light period, suggesting that the duration of ovulation was less than two hr. Under lighting from 15: 00 to 03: 00 (LD12: 12), the animals ovulated between 11: 00 and 15: 00, and the time required for ovulation was 4hr 28min. Under lighting from 18: 00 to 03: 00 (LD9: 15) or 15: 00 to 06: 00 (LD 15: 9), the time required for ending the ovulation were 5h 23min and 3h 52min, respectively. From these results it was considered that, under shorter daily lighting time required from the onset to ending of ovulation tends to become longer than in the case of 12 hours of lighting, while it tends to become shorter under longer lighting period.

View full abstract

The oxygen uptake and heat production of four male cynomolgus monkeys (Macaca irus) of 6-7 years of age weighing 6.4-7.6 kg in a primate restraining chair were determined at ambient temperature (Ta) of 25°C and 10°C. The average oxygen uptake and heat production at Ta=25°C were 637.7ml/kg/hr (STPD) and 3.2kcal/kg/hr, respectively which were elevated to 919.3ml/kg/hr (STPD) and 4.4kcal/kg/hr at Ta=10°C.

View full abstract

Kittens could be declawed by ligation between the second and third phalanxes under light anesthesia. No regeneration was observed one year after the procedure.

View full abstract

The monkey is usually apt to resist against squeezing when we use an old-fashioned squeezingcage, having a back-panel movable toward the front side. This brief note deals with a newly-devised monkey cage, having a front panel which can be moved toward the back of the cage, being guided by 4 rails set inside the cage (Fig. 1) . The animal can easily be restrained between the back and the moved front panel of the cage. In addition, this new type cage has not any parts which are difficult to be washed and disinfected.

View full abstract