Cuboidal epithelium of thin segment were revealed in the late stage of embryonic kidney and apoptosis occured after birth, especially in the seventh day after birth.

• 上皮由立方细胞逐渐发育成扁平细胞过程中，细胞凋亡起着很大作用。细胞凋亡高峰时间发生在生后七天左右。