Merviel P, Evain-Brion D, Challier J C, Salat-Baroux J, Uzan S
Department of Gynaecology, Obstetrics and Reproductive Medicine, Hôpital Tenon, Paris, France.
Zentralbl Gynakol. 2001 Jun;123(6):328-39. doi: 10.1055/s-2001-16283.
The implantation of the human embryo is a double paradox, immunological and biological. The immunological paradox is that it consists of a heterologous graft in which the uterine immune system (via the cytokines) and the embryo's antigenicity (HLAG) collaborate to make possible both implantation and the maintenance of the pregnancy. The biological paradox arises because several different mechanisms must be successively implemented for these two epithelia to fuse and then for one to allow invasion by the other (that is, the for the endometrium to be decidualized by the trophoblast): preparation of the endometrium throughout the menstrual cycle under the influence of estrogens and then progesterone, with the involvement of growth factors (EGF, TGF and IGF), neoangiogenesis (estradiol, FGF and VEGF), recognition by the trophoblastic cells of the various components of the decidua and of the extracellular matrix (integrins and cadherin) and the progressive invasion of the decidua, to the depth of the spiral arteries (by the trophoblastic secretion of metalloproteases). A defective or excessive trophoblastic invasion can result in complications of pregnancy: early spontaneous miscarriage, preeclampsia and growth retardation of vascular origin in the case of defects, placenta accreta or percreta in the case of excess.
人类胚胎着床存在双重悖论，即免疫悖论和生物学悖论。免疫悖论在于，胚胎着床是一种异源移植，其中子宫免疫系统（通过细胞因子）与胚胎抗原性（人类白细胞抗原G）共同作用，使着床和维持妊娠成为可能。生物学悖论的产生是因为为了使这两种上皮细胞融合，然后使其中一种上皮细胞允许另一种上皮细胞侵入（即让滋养层使子宫内膜蜕膜化），必须相继实施几种不同的机制：在整个月经周期中，在雌激素和孕激素的影响下，子宫内膜进行准备，生长因子（表皮生长因子、转化生长因子和胰岛素样生长因子）参与其中，新生血管生成（雌二醇、成纤维细胞生长因子和血管内皮生长因子），滋养层细胞识别蜕膜和细胞外基质的各种成分（整合素和钙黏蛋白），以及滋养层逐渐侵入蜕膜，直至螺旋动脉深处（通过滋养层分泌金属蛋白酶）。滋养层侵入存在缺陷或过度，可能导致妊娠并发症：缺陷时会出现早期自然流产、先兆子痫和血管源性生长迟缓，过度时会出现胎盘植入或穿透性胎盘植入。
