The Hormone That Causes Ejection of Milk into the Mammary

Question

The hormone that causes ejection of milk into the mammary ducts is:
A)prolactin.
B)estrogen.
C)oxytocin.
D)progesterone.

Accepted Answer

The hormone that causes ejection of milk into the mammary ducts is oxytocin. Oxytocin is released from the posterior pituitary gland in response to nipple stimulation or the sound of a crying baby. It causes the muscles around the mammary glands to contract and push the milk into the ducts for release through the nipple. Prolactin is the hormone responsible for milk production, but it does not directly cause milk ejection. Estrogen and progesterone are involved in preparing the breast for lactation, but do not play a direct role in milk ejection.