Table 2.

Physiological effects of estrogen in various female organs.

Female organs	Physiological effects of estrogen
Breast	Estrogen is responsible for the development of mammary gland tissue and parenchymal and stromal changes in breast tissue at puberty in females. Estrogen is also responsible for the development of mammary ducts during puberty and, during pregnancy, functions to secrete breast milk in postpartum lactation.
Uterus	In the uterus, estrogen helps to proliferate endometrial cells in the follicular phase of the menstrual cycle, thickening the endometrial lining in preparation for pregnancy.
Vagina	Estrogen supports the proliferation of epithelial mucosa cells of the vagina and the vulva. In the absence of estrogen, the vaginal and vulvar mucosal epithelium becomes thin and presents with symptoms of dryness known as vulvovaginal atrophy.