THE RELATIVE GROWTH OF THE MAMMARY GLAND IN NORMAL, GONADECTOMIZED AND ADRENALECTOMIZED RATS

Abstract

In the female rat, over the range of body wt. increase (7-45g.) which occurs between the ages of 2-23 days, the specific growth rate in the mammary gland area is the same as that of the body surface as a whole. At approx. 23 days of age, the mammae come under the influence of ovarian hormones and the phase of isometry changes to one of positive allometry, the specific growth rate of the glands becoming 3 times that of the body surface. Ovariectomy at the 22d day of age is followed by isometric growth of the mammary glands. Adrenalectomy of the intact female rat at 22 days of age results in no significant alteration in the relative growth rate of the mammary gland. In the male rat, over the body-wt. range of 7-344g., the mammary-gland growth rate shows a very slight positive allometry ([alpha]= 1.11 [plus or minus] 0.03). Castration at the 22d day has no significant effect, and adrenalectomy of the male rat causes only a slight increase of doubtful significance in the relative growth of the mammary gland.