Regulation of Mammary Development and Lactation

Abstract

The mammary gland is unique, not only in its secretory products, but in its ability to complete an entire cycle of growth and differentiation each time it is called upon to provide nutrition for a new set of offspring. For this reason, in this chapter, the hormonal control of mammary development and the coordination of mammary function with other events in the female reproductive cycle are considered, along with the regulation of milk secretion and ejection. The focus will be on hormonal controls as they are understood in the human, drawing on animal studies when necessary for clarity or when information from humans is lacking. This chapter is intended to provide an overview of the complex hormonal interactions which regulate mammary function at the organismic level, making the general principles accessible to the nonspecialist. The hormonal control of mammary development will be discussed, followed by a description of prolactin secretion through the female life cycle and the role of oxytocin in milk ejection. Finally, the effects of breast-feeding on fertility and our current understanding of the interaction between nutrition and lactation will be outlined.