Throughout the menstrual cycle, the breasts are enlarged by premenstrual water retention and temporary advancement as affected by switching hormone concentrations.[fifty five] Breast tissue starts to type in the fourth 7 days of fetal lifestyle. In the fetus, breast tissue develops alongside two "milk lines" that get started with the https://grok.com/share/c2hhcmQtMw%3D%3D_21b4ddf4-c274-418a-a078-c9d2af4898ff