Optometry Admission Test (OAT) Practice

Prolactin is the hormone primarily responsible for the stimulation of milk secretion. It is produced in the anterior pituitary gland and plays a crucial role in the lactation process. During pregnancy, prolactin levels rise, preparing the mammary glands for milk production. After childbirth, increased prolactin secretion facilitates milk synthesis and secretion in response to the infant's suckling.

This hormone acts on the mammary glands to promote the development of mammary tissue and initiate and maintain lactation. Its effects are particularly evident when a mother breastfeeds, as the physical act of suckling triggers further release of prolactin, ensuring an adequate milk supply for the infant.

Other hormones listed, such as ACTH, TSH, and LH, play significant roles in different bodily processes but do not directly influence milk secretion. ACTH is involved in the stress response and stimulates cortisol release; TSH regulates thyroid function and metabolism; LH is crucial for reproductive processes, particularly in ovulation and testosterone production. Thus, prolactin is distinctively responsible for the stimulation of milk secretion post-delivery, making it the correct answer.