Sherman M I, Atienza-Samols S B
J Embryol Exp Morphol. 1979 Aug;52:127-39.
We have separated for enzyme analysis the following layers that surround the conceptus at midgestation: decidua, trophoblast, parietal endoderm (including Reichert's membrane), visceral endoderm, yolk-sac mesoderm and amnion. Measurement of several catabolic enzyme activities (N-acetyl-beta, D-hexosaminidase, beta-glucuronidase, alkaline and acid phosphatases and non-specific esterases) in these tissues indicates that they are biochemically distinct, perhaps reflecting the different functions that they perform in providing the embryo proper with a desirable environment for differentiation and development. Our studies also provide an example of how visceral endoderm cells can effectively block passage of maternal macromolecules (in this case a serum esterase) in the fetal circulation. Finally, since there is often difficulty in distinguishing among early embryonic and extra-embryonic cell types produced in teratocarcinoma cultures, we have considered how our observations might be of use in the respect, particularly in discriminating between visceral and parietal endoderm.
蜕膜、滋养层、壁内胚层（包括瑞氏膜）、脏内胚层、卵黄囊间皮和羊膜。对这些组织中几种分解代谢酶活性（N-乙酰-β-D-氨基己糖苷酶、β-葡萄糖醛酸酶、碱性和酸性磷酸酶以及非特异性酯酶）的测定表明，它们在生化性质上有所不同，这或许反映出它们在为胚胎提供适宜分化和发育环境中所发挥的不同功能。我们的研究还提供了一个实例，说明脏内胚层细胞如何能够有效阻断母体大分子（在此为一种血清酯酶）在胎儿循环中的通过。最后，由于在区分畸胎瘤培养物中产生的早期胚胎和胚外细胞类型时常常存在困难，我们思考了我们的观察结果在这方面可能有何用途，特别是在区分脏内胚层和壁内胚层方面。
