| 2. | Mammary gland is a unique organ , which can postnatally regenerate , terminally differentiate , and involute upon successive cycle of pregnancy , lactation , and involution , respectively , and provides an optimal model for the study of organogenesis , differentiation , apoptosis , and pattern formation involved in development 哺乳动物的乳腺是唯一在动物出生后可以多次再生、退化的器官。不同发育时期的动物乳腺中都存在一定比例的干细胞,正是这些干细胞维持和保证了乳腺发育的特性。 |