Blackburn D G, Taylor J M, Padykula H A
Department of Cell Biology, School of Medicine, Vanderbilt University, Nashville, Tennessee 37232.
J Morphol. 1988 May;196(2):127-36. doi: 10.1002/jmor.1051960203.
Available evidence provides little support for a recent proposal that the term "trophoblast" be applied solely to eutherian mammals. Arguments for such a restricted usage are based on a dichotomous interpretation of therian reproduction that underestimates the developmental, structural, and functional diversity of trophoblastic tissues occurring within the infraclass Eutherian. The occurrence of developmental patterns that are phenotypically intermediate between those of commonly studied eutherians and metatherians suggests that blastocyst development is not fundamentally different in marsupials and eutherians. The trophoblast of marsupials accomplishes most or all of the major functions of the eutherian trophoblast, including maternal-fetal physiological exchange, implantation, contribution to placental membranes, steroid metabolism, and possibly, immunological protection of the conceptus. Furthermore, application of the term "trophoblast" to marsupials is consistent with present and past usage, as well as with the original definition and etymological derivation of the term. Therefore, we recommend that the term "trophoblast" continue to be applied in a functional-morphological sense to the appropriate extraembryonic tissues of marsupials. Such use of functional (rather than taxonomic) criteria for application of this term avoids biasing interpretations of mammalian reproductive evolution.
现有证据几乎无法支持最近一项提议，即“滋养层”一词应仅用于真兽类哺乳动物。这种限制使用的论据基于对兽亚纲生殖的二分法解释，这种解释低估了真兽下纲内滋养层组织的发育、结构和功能多样性。在通常研究的真兽类和后兽类之间出现的表型中间发育模式表明，有袋类和真兽类的囊胚发育并没有根本差异。有袋类的滋养层完成了真兽类滋养层的大部分或所有主要功能，包括母胎生理交换、着床、对胎盘膜的贡献、类固醇代谢，以及可能对胚胎的免疫保护。此外，将“滋养层”一词应用于有袋类与当前和过去的用法一致，也与该词的原始定义和词源派生一致。因此，我们建议“滋养层”一词继续在功能形态学意义上应用于有袋类适当的胚外组织。使用这种功能（而非分类学）标准来应用该术语可避免对哺乳动物生殖进化的解释产生偏差。
