Weight and vaginal opening in the albino rat

Abstract

The body weight of rats of spontaneous vaginal opening (W(VO)) was related to the weight of weaning (W(W)) and the time elapsed between the two events (t(VO)) by the following equation: W(VO) = a(j) + bW(W) + ct(VO) + residual where a(j) is the litter effect present when both male and female young are reared together. When only female young are raised, a(j) may be replaced by a, so that in this instance there is no litter effect. Further model differences were noted for young raised under different conditions.