part of mammary stem cell proliferation The expansion of a mammary stem cell population by cell division. Mammary stem cells are a source of cells for growth of the mammary gland during puberty and gestation. These cells can give rise to both the luminal and myoepithelial cell types of the gland, and can regenerate the entire organ. hjd 2010-09-14T01:19:45Z GO:0002174 biological_process cell population proliferation mammary gland development