Lactogen, or prolactin, is a chemical sent directly into the blood stream by the PITUITARY gland. It stimulates the production of milk in mammals.
During pregnancy, an organ called the placenta is formed. It enables the mother to feed the developing baby, and also secretes a hormone known as ESTROGEN. Another hormone, progesterone, is also secreted during pregnancy. The amount of estrogen and progesterone present is great enough to prevent the secretion of the milk-forming hormone (lactogen) by the pituitary. After birth of the baby, the placenta is lost, and the amount of estrogen secreted is much
less. The amount of progesterone is also less. As a result, lactogen begins to be secreted, and milk is produced by the mammary glands.
