Programmed cell death in the terminal endbud

Ductal development in the pubertal mouse mammary gland is characterized by dramatic morphological changes in the epithelium driven by proliferation of cap and body cells in the terminal endbuds. Recent experiments revealed a coincident and abundant apoptosis in the body cells of these structures. Th e cells undergoing apoptosis are occasionally restricted to defined regions within the terminal endbud. Localization adjacent to the presumptive lumin a suggests that this process functions to sculpt the lumina of the subtendi ng duct. Members of the Bcl-2 family of apoptosis regulatory molecules; Bcl -2 and Bcl-x, appear to have some role in regulating apoptosis in the termi nal endbud. Other possible signals which could regulate this developmental process and a model are presented.