The central nervous system, neurohypophysis and milk ejection

Abstract

Lactation may be divided into two main phases. First, milk secretion which consists of the synthesis of milk by the cells of the alveolar epithelium and the passage of the milk from the cytoplasm of these cells into the alveolar lumen. And secondly, milk removal from the mammary gland. A small part of the milk may be withdrawn from the mammary gland by suckling young in the absence of any active process on the part of the maternal animal, passive withdrawal ; but the greater part of the contained milk requires for its removal the participation of a neurohumoral reflex resulting in contraction of mammary tissue and thereby expulsion of contained milk. This active process is called milk ejection .