Mammary Gland Development

The mammary gland undergoes drastic changes throughout the lifetime of a female. The development of the organ can be divided into the following stages: fetal, prepubertal, pubertal, pregnancy, lactation, and involution. During each stage hormones induce morphological changes in the epithelium and remodeling of the stroma. Herein, we succinctly describe the major developmental events in the human breast and the rodent mammary gland, in particular the mouse, which is the more thoroughly studied experimental model for mammary gland development. Steroidal and pituitary hormones play important roles during prepubertal, pubertal, and adult periods of mammary gland morphogenesis. Remarkably, in addition to the well-known fact that exposure to ovarian hormones during the lifetime of a woman is a major risk factor for breast cancer, the gland seems to be even more vulnerable to exogenous hormones and endocrine disruptors during the fetal and the neonatal period.