Which hormone is responsible for milk ejection (let-down)?

Which hormone is responsible for milk ejection (let-down)?

• A. Prolactin
• B. Oxytocin
• C. Estrogen
• D. Melatonin

Answer: (B)

Milk ejection, or let-down, is driven by oxytocin released from the posterior pituitary in response to nipple stimulation during suckling. Oxytocin acts on the myoepithelial cells that surround the milk-producing alveoli, causing these cells to contract and push milk into the ducts toward the nipple. This is the reflex that actually ejects milk, while another hormone, prolactin, is responsible for producing milk in the glands. Estrogen helps prepare breast tissue for lactation but does not trigger let-down, and melatonin has no direct role in the lactation process. In practical terms, anything that enhances or inhibits oxytocin release (like the infant's latch, crying, or maternal stress) can affect the ease of milk let-down.

Milk ejection, or let-down, is driven by oxytocin released from the posterior pituitary in response to nipple stimulation during suckling. Oxytocin acts on the myoepithelial cells that surround the milk-producing alveoli, causing these cells to contract and push milk into the ducts toward the nipple. This is the reflex that actually ejects milk, while another hormone, prolactin, is responsible for producing milk in the glands. Estrogen helps prepare breast tissue for lactation but does not trigger let-down, and melatonin has no direct role in the lactation process. In practical terms, anything that enhances or inhibits oxytocin release (like the infant's latch, crying, or maternal stress) can affect the ease of milk let-down.