Agorastos T, Bär T, Grussendorf E I, Liedtke B, Lamberti G
Z Geburtshilfe Perinatol. 1981 Apr;185(2):111-5.
The surface layer of fetal epidermis in early pregnancy, the Periderm, is progressingly replaced by the final keratinization process during fifth to sixth month of gestation. Then the peridermal cells are shed into the amniotic fluid. It is still controversial, whether complete peridermal cells or just their globular protrusions are separated. Formation of mikrovilli and invaginations of plasma membrane, the numerous smaller and larger vacuoles and the cytoplasmatic meshwork of fine filaments without production of keratohyaline, are characteristics of peridermal cells, and are described in detail by electron microscopical investigations on cells suspended in the amniotic fluid, which are most likely of peridermal origin.
妊娠早期胎儿表皮的表层，即周皮，在妊娠第五至六个月期间通过最终的角质化过程逐渐被取代。然后周皮细胞脱落到羊水中。究竟是完整的周皮细胞还是仅仅是它们的球状突起被分离出来，这仍然存在争议。微绒毛的形成、质膜的内陷、众多大小不一的液泡以及没有透明角质颗粒产生的细丝状细胞质网络，是周皮细胞的特征，通过对悬浮在羊水中的细胞进行电子显微镜研究得以详细描述，这些细胞很可能起源于周皮。
