Dietary Regulation of Allometric Ductal Growth in the Mammary Glands

Development of the mammary glands is a continual process spanning from prenatal establishment of the epithelial primordium through to the full establishment of the secretory gland during lactation and its subsequent regression during involution. While the accretion of parenchymal tissue is greatest during phases such as gestation, it is the growth and establishment of the mammary ductal network prior to and during puberty that sets the stage for all subsequent periods of development and function. Depending on the species, ductal elongation can involve large amounts of epithelial proliferation and apoptosis in terminal end bud structures that interface with the surrounding stromal microenvironment. Ultimately all these processes are considered to be driven by a changing endocrine environment – but is it that simple? Of course, postnatal development also occurs against a changing nutritional background. Our findings from various models emphasize that dietary nutrients and plane of nutrition can dramatically impact mammary growth – either positively or negatively. We will review some of these key findings and summarize the potential for alternate mechanisms of ductal growth regulation in the mammary glands across species.