Lactation
Start with the big picture
Mammary glands contain lobules made up of alveoli and ducts. Epithelial cells produce milk, while surrounding myoepithelial cells contract to help eject it. During development, estrogen stimulates ductal growth and progesterone promotes alveolar development; prolactin and human placental lactogen support overall maturation. Milk secretion is restrained during pregnancy by high estrogen and progesterone. After delivery, their levels decline and prolactin supports the start of milk production. Nipple stimulation during suckling increases prolactin and oxytocin: prolactin supports production, while oxytocin triggers the let-down reflex. Prolactin also inhibits GnRH, reducing LH and FSH and contributing to natural contraception during exclusive breastfeeding.
What you'll learn
- Describe the roles of alveoli, ducts, epithelial cells, and myoepithelial cells.
- Explain how estrogen, progesterone, prolactin, and human placental lactogen support breast development.
- Outline why milk production begins postpartum.
- Distinguish prolactin’s role in milk production from oxytocin’s role in milk ejection.
- Summarize how prolactin influences GnRH, LH, and FSH during exclusive breastfeeding.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
