Induction of Mammary Growth in Rats by Estrogen and Progesterone.,

Abstract

The administration of estrogen and progesterone to castrate female rats for 15 days or more stimulated an increase of desoxyribose nucleic acid (DNA) comparable to that found at a corresponding period of pregnancy. Continued injection to 32 days increased only slightly the DNA content, indicating a cessation of further gland proliferation. In the hormone stimulated glands the PNA content increased comparable to pregnancy but since profuse lactation was not stimulated it did not increase compared to the level in the latter stages of pregnancy or lactation. However, when the hormones were given for 26 days and then stopped, lactation set in sufficiently profuse to nourish foster litters of rats.