Mammary ductal and alveolar development: Lesson learned from genetically manipulated mice

The mammary gland has been an area of great interest to developmental biolo gists for many years because its formation involves many fundamental proces ses that are central to the development of other organs. Although mammary d evelopment has been well described structurally, the molecules and signalin g mechanisms that are involved are still largely undefined. For the last se veral years, intensive effort has been made to understand the molecular mec hanisms involved in mammary development. With the recent advances in transg enic and knockout technologies, the ability to delete and/or alter the expr ession of certain genes in the mouse genome has allowed us to begin to eluc idate the mechanisms underlying mammary gland development. In this review, we discuss several mouse models that have provided insight into the molecul es and signaling mechanisms that govern ductal development and lobuoloalveo lar differentiation in the mammary gland. (C) 2001 Wiley-Liss. Inc.