Seo Heewon, Melo Gabriela D, Oliveira Ramiro V, Franco-Johannsen Gessica, Bazer Fuller W, Pohler Ky, Johnson Gregory
H Seo, Department of Veterinary Integrative Biosciences, Texas A and M University, College Station, United States.
G Melo, Department of Animal Science, Texas A and M University, College Station, United States.
Reproduction. 2023 Dec 1;167(2). doi: 10.1530/REP-23-0444.
What we understand about early stages of placentation in cattle is based on an elegant series of electron microscopic images that provide exquisite detail, but limited appreciation for the microanatomy across the utero-placental interface. In order to achieve a global perspective on the histology of bovine placentation during critical early stages of gestation, i.e., days 21, 31, 40, and 67, we performed immunohistochemistry to detect cell-specific expression of pregnancy-associated glycoprotein (PAG), cytokeratin, epithelial (E)-cadherin, and serine hydroxymethyltransferase 2 (SHMT2) at the intact utero-placental interface. Key findings from the immunohistochemical analyses are that there are: (1) PAG-positive cells with a single nucleus within the uterine luminal epithelial (LE) cells; (2) PAG-positive cells with two nuclei in the LE; (3) PAG-positive syncytial cells with more than three nuclei in the LE; (4) LE cells that are dissociated from one another and dissociated from the basement membrane in regions of syncytialization within the LE layer; (5) replacement of the mononuclear LE with a multi-layer thick population of PAG-positive cells invading into the uterine stroma of caruncles, but not into the stroma of intercaruncular endometrium; and (6) PAG-, E-cadherin- and SHMT2-positive mononuclear cells at the leading edge of developing cotyledonary villi that eventually represent the majority of the epithelial surface separating caruncular stroma from cotyledonary stroma. Finally, the utero-placental interface of ruminants is not always uniform across a single cross-section of a site of placentation which allows different conclusions to be made depending on the part of the utero-placental interface being examined.
我们对牛胎盘形成早期阶段的了解，是基于一系列精美的电子显微镜图像，这些图像提供了精致的细节，但对子宫-胎盘界面的微观解剖结构的认识有限。为了全面了解妊娠关键早期阶段（即第21天、31天、40天和67天）牛胎盘形成的组织学情况，我们进行了免疫组织化学检测，以检测完整子宫-胎盘界面处妊娠相关糖蛋白（PAG）、细胞角蛋白、上皮（E）-钙黏蛋白和丝氨酸羟甲基转移酶2（SHMT2）的细胞特异性表达。免疫组织化学分析的主要发现如下：（1）子宫腔上皮（LE）细胞内有单个核的PAG阳性细胞；（2）LE中有两个核的PAG阳性细胞；（3）LE中有三个以上核的PAG阳性合体细胞；（4）在LE层合体化区域，LE细胞彼此分离并与基底膜分离；（5）单核LE被多层厚的PAG阳性细胞取代，这些细胞侵入肉阜的子宫基质，但不侵入肉阜间子宫内膜的基质；（6）在发育中的子叶绒毛前缘有PAG、E-钙黏蛋白和SHMT2阳性的单核细胞，这些细胞最终代表了将肉阜基质与子叶基质分隔开的上皮表面的大部分。最后，反刍动物的子宫-胎盘界面在胎盘形成部位的单个横切面上并不总是均匀的，这使得根据所检查的子宫-胎盘界面的不同部分可以得出不同的结论。
