Hormone for Alveolar Growth of Mammary Gland

The hormone responsible for the alveolar growth of the mammary gland is:

Correct Answer: Progesterone

Progesterone is responsible for the alveolar (lobulo-alveolar) growth of the mammary gland — the secretory alveoli that actually produce milk.

Mammary Gland Development — Hormonal Control

• Duct system growth: Estrogen — stimulates growth and branching of the ductal system.
• Alveolar (lobulo-alveolar) growth: Progesterone — stimulates development of secretory alveoli (milk-producing units). ✔
• Milk secretion (lactogenesis): Prolactin — triggers actual milk synthesis after parturition.
• Milk ejection (let-down): Oxytocin — released by suckling stimulus → smooth muscle contraction of myoepithelial cells → milk ejection.

Memory Tip

'Estrogen = ducts, Progesterone = alveoli (Producing units), Prolactin = production, Oxytocin = outflow'