Abstract
A study of the pituitary lactogen content of the albino mouse was presented. The lactogen content of the pituitary of the virgin O is relatively low. By the 10th day of pregnancy there is an 88% increase in pituitary lactogen on the basis of 100 g. of body wt. which is followed by an additional increase of 63% following parturition. A peak, 201% above the level for the virgin [female], is reached by the 5th day post partum after which the lactogen content declines rapidly. At the 21st day post partum the lactogen level is 38% above that of the virgin [female]. With the exception of a high lactogen level during pregnancy, the lactogen curve for the mouse pituitary closely follows that for other species previously reported. Neither ovariectomy nor thyroxine injs. alone into [female][female] altered the pituitary lactogen content.