Changes

Mammary gland development is initiated prenatally in the female foetus and continues through puberty and pregnancy.  The anatomy and distribution of mammary glands is diverse among mammals.  Secretion of milk does not begin until shortly (hours) before parturition.  Lactation provides the neonate with the opportunity to  nurse and be nourished with minimal energy expenditure.  It also provides immunoprotection for the neonate because initial mammary secretions (colostrum) contain antibodies that provide passive immunity.  Lactation continues until the neonate is weaned.  After weaning, the mammary glands undergo involution and return to a non-secretory state.

Mammary gland development is initiated prenatally in the female foetus and continues through puberty and pregnancy.  The anatomy and distribution of mammary glands is diverse among mammals.  Secretion of milk does not begin until shortly (hours) before parturition.  Lactation provides the neonate with the opportunity to  nurse and be nourished with minimal energy expenditure.  It also provides immunoprotection for the neonate because initial mammary secretions (colostrum) contain antibodies that provide passive immunity.  Lactation continues until the neonate is weaned.  After weaning, the mammary glands undergo involution and return to a non-secretory state.