Pubertal mammary gland development: insights from mouse models.

During puberty the mammary gland develops from a rudimentary tree to a branched epithelial network of ducts which can support alveolar development and subsequent milk production during pregnancy and lactation. This process involves growth, proliferation, migration, branching, invasion, apoptosis and above all, tight regulation which allows these processes to take place simultaneously during the course of just a few weeks to create an adult gland. The process is under hormonal control and is thus coordinated with reproductive development. Mouse models, with overexpressed or knocked-out genes, have highlighted a number of pubertal mammary gland phenotypes and given significant insight into the regulatory mechanisms controlling this period of development. Here we review the published findings of the wide range of gene-manipulated mammary mouse models, documenting the common pubertal mammary gland phenotypes observed, and summarizing their contribution to our current understanding of how pubertal mammary gland development occurs.