Ferro E A, Bevilacqua E
Department of Morphology, University of Uberlândia, MG, Brazil.
J Morphol. 1994 Aug;221(2):139-52. doi: 10.1002/jmor.1052210204.
Implantation sites in the uterus of the cricetid rodent Calomys callosus were examined by light and electron microscopy at several points during day 4 of pregnancy to determine the changes occurring in the trophoblast and epithelial cells during the early blastocyst-endometrial relationship, particularly the epithelial removal phase. By morning, the blastocysts had already lodged in the antimesometrial region of the uterine crypts and the embryo-maternal interaction was limited to sparse contacts between the epithelial microvilli and the trophoblast surface. A few dense and altered epithelial cells were present. Three zones could be distinguished in the stromal region. In the subepithelial area, the stromal cells showed features similar to those found in other rodents during the early decidualization process. Effective epithelial invasion by the trophoblast occurred only in the evening, although at noon, apposition and attachment phases were identifiable. During invasion, the trophoblast processes were first seen insinuating between the epithelial cells, projecting towards the basal lamina, and finally replacing these cells. The epithelial cells in contact with the invading trophoblast exhibited severe disorganization similar to that found during the process of cell death by apoptosis. The removal of such cells occurred by trophoblast phagocytosis. Once in contact with the basal lamina, the trophoblast rapidly spread out both mesometrially and antimesometrially, phagocytosing the remaining epithelial cells. Trophoblast processes were also seen penetrating the basal lamina. Given that the epithelium breached and phagocytosed by the trophoblast habitually displays degenerative characteristics, we consider the mechanisms that might be involved in epithelial cell death and in the removal of the uterine epithelium, and the participation of the trophoblast in both these events.
在妊娠第4天的几个时间点，通过光学显微镜和电子显微镜检查了仓鼠科啮齿动物南美原鼠子宫内的着床部位，以确定在早期囊胚与子宫内膜关系，特别是上皮清除阶段，滋养层和上皮细胞中发生的变化。到上午时，囊胚已经着床于子宫隐窝的反系膜区域，胚胎与母体的相互作用仅限于上皮微绒毛与滋养层表面之间的稀疏接触。存在一些致密且改变的上皮细胞。在基质区域可区分出三个区域。在上皮下区域，基质细胞呈现出与其他啮齿动物在早期蜕膜化过程中发现的特征相似的特征。滋养层对上皮的有效侵入仅在傍晚发生，尽管在中午时，可以识别出贴附期和附着期。在侵入过程中，首先看到滋养层突起插入上皮细胞之间，向基膜突出，最终取代这些细胞。与侵入的滋养层接触的上皮细胞表现出严重的紊乱，类似于在细胞凋亡导致的细胞死亡过程中发现的紊乱。此类细胞的清除通过滋养层吞噬作用发生。一旦与基膜接触，滋养层迅速向系膜侧和反系膜侧扩散，吞噬剩余的上皮细胞。还可见滋养层突起穿透基膜。鉴于被滋养层破坏和吞噬的上皮通常表现出退化特征，我们考虑了可能参与上皮细胞死亡和子宫上皮清除的机制，以及滋养层在这两个事件中的参与情况。
