To define the standard for the normal physiological status of rats, about 300 Wistar strain rats, bred in our department, were examined for body weight gain with age in day, and weight of 11 organs-hypophysis, thyroid, adrenal, thymus, testis, ovary, uterus, heart, liver, spleen and kidney-were obtained for each body weight group. And the results were compared with Donaldson's report.
As to body weight gain, our results approximately agreed with Donaldson's, but seemed rather lower as compared with recent growth curve for rats.
As to correlation of body weight to weight of thymus, testis and ovary, our results tended to differ remarkably high in the latter. Weight of hypophysis and adrenal were evidently higher in females than in males, whereas those of thymus and kidney were conversely higher in male. In adrenal weight, there were remarkable differences between right and left side, the left exceeding the right without regard to sex.
Female rats were examined for vagina opening and the first estrus, and from these results and organ weight increase, the puberty for sex was estimated to range 4575 days of age.
Further, some discussions were made on whether it is reasonable to express the weight of the organ in ratio to body weight.
