ABSTRACT
Lactational biology is a specialty area of mammalian physiology that has much in common with reproductive physiology, nutrition, metabolism, growth, and development. A comprehensive treatment of lactational biology begins with embryologic differentiation of ectodermal cells into the primitive mammary streak, a process that occurs about the time that the embyro assumes a C-shaped form, early in gestation. As there will be much reference to the histological elements of the mammary gland, a description of the various tissues making up the mature gland. The process of development of mammary tissue is described by the term mammogenesis. Mammogenesis can be conveniently considered in five phases: fetal, prepuberal, postpuberal, pregnancy, and early lactation. Prenatal development begins very early, with organogenesis of what will become mammary tissue taking place just a few weeks after conception. The mammary gland is also capable of taking up ketone bodies, particularly beta-hydroxybutyric acid, and converting them into butyric acid for milk fat synthesis.
