During breastfeeding, an infant's suckling triggers milk ejection within about 30 seconds. Which statement correctly describes the neuroendocrine pathway involved?

• A Suckling afferents stimulate dopamine release into the portal circulation, which contracts myoepithelial cells
• B Suckling releases oxytocin continuously from the anterior pituitary under prolactin control
• C Suckling directly depolarises myoepithelial cells through local neural reflex arcs in the breast
• D Suckling afferents ascend via spinal cord to the PVN and SON, causing pulsatile oxytocin release from the posterior pituitary ✓

Explanation

The milk ejection reflex is a classic neuroendocrine reflex: nipple afferents travel through spinal nerves to the brainstem and hypothalamus, exciting magnocellular PVN and SON neurons that fire in bursts, releasing stored oxytocin from posterior pituitary nerve terminals. Oxytocin then contracts breast myoepithelial cells. Oxytocin is made only in the hypothalamus and released by the posterior pituitary, so option B fails on source, and dopamine inhibits rather than mediates the reflex.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.