抄録
Twenty-one-day-old male rats of the Donryu-strain supplied by the Central Laboratories for Experimental Animals were fed CLEA chow CE-2 in our airconditioned animal house.
Animals were observed clinlcally and autopsied at the age of 21-180 days.
1. At autopsy, the body weight, body and tail length were measured. In the growth curve of the body weight, a plateau was seen after 80 days and in the case of body and tail length it was seen after 50 days. Curves showing increase of organ weights are presented in Fig. 5-A-5-F. The weight curves are plateaued respectivey after 50 days in thyroid, submaxillarry glands, stomach, liver, heart, and brain, after 70 days in testis, ventral prostates, adrenals and hypophysis, after 80 days in epididymides, pancreas and M. levator ani, after 90 days in fat bodies. The weight of thymus showed a peak at 50 days of age and decreased there after.
2. The period of sexual maturity was estimated to be 50 days of age, because the matured sperms were observed in epidymal tail.
3. During 22nd-87th day, there was no significant difference in the ratio of the fecal weight and the food intake.
4. Zonary thing of back hair along the spinal column was observed frequently in animals of 35-47 days of age.
5. Accessory adrenals were detected in 62.8% of rats. Deformity of kidney were observed in 2 out of 498 cases. Testicular atrophy was observed in 40 out of 60 cases after 140 days of age.
6. During 50-90 days of age, chronic nasal infection was observed in an appreciable number of rats which resulted the death of some animals due to acute pneumonia.
