Final answer:
True, oxytocin stimulates the ejection of milk from the mammary glands by contracting myoepithelial cells surrounding the milk-producing alveoli, leading to what is known as the 'let-down' reflex.
Step-by-step explanation:
The statement that the ejection of milk from the mammary glands is stimulated by the hormone oxytocin is true. When a baby nurses, sensory nerve impulses from the areola are sent to the mother's hypothalamus. This signal triggers the posterior pituitary to release oxytocin, which then causes the myoepithelial cells around the mammary alveoli to contract. As these cells contract, milk is pushed from the alveoli into the lactiferous ducts. From the lactiferous ducts, milk collects in the lactiferous sinuses and is ejected through the nipple pores.
Oxytocin release and the subsequent milk ejection is a response to infant suckling and is part of a positive feedback loop that encourages more suckling and milk production. The milk ejection reflex is commonly referred to as the “let-down” reflex. This is important for breastfeeding as it delivers the necessary nutrients and immunoglobulins to the infant, which are crucial for growth and protection against infections.