常见的2吴洁——孕激素与成功妊娠的维持.pptVIP

* * 在月经周期的后半期，子宫内膜必须在足够孕酮分泌的支持下才能实现向分泌相的转化。 雌激素和孕酮之间的相互作用由下丘脑和垂体的分泌物控制，又受雌激素和孕酮自身负反馈调节。 The diagram shows a pre-implantation-stage blastocyst (approximately 6 -7 days after conception) and the tightly networked processes thought to be necessary for uterine receptivity and blastocyst apposition and adhesion. COX-2 = cyclooxygenase-2 EGF = epidermal growth factor LIF = leukemia inhibiting factor Progesterone (bended arrow) plays a crucial role not only in preparing the endometrial stroma for the successful blastocyst adhesion But also in pathways involving cytokines prostaglandin Source Norwitz et al., N Engl J Med, 2001 * After pointing out pathways of pregnancy protection, involving the HLA-G, IDO or uterine natural killer cells, one might ask: what causes the failure of protecting the fetus and leads embryo rejection? * There are quite a number of different pathways involved in the rejection of a fetus by its mother, but three, in particular, are of special importance. These pathways are mediated by: Antibodies T helper (Th1) cells Natural Killer (NK) cells * The first pathway in abortion or embryo destruction due to immunologic interaction is mediated through symmetric antibodies. Symmetric Antibodies : An antibody is like a ‘Y’, made up of 2 Fab parts and 1 Fc part. The Fab parts, which form the double arms of the ‘Y’, bind with the fetal antigen. Thereafter, the Fc part which forms the single arm of the ‘Y’ binds with the complement component C1q leading to activation of the complement cascade. This results in cytotoxic and phagocytic reactions, eventually causing destruction of the fetus. Asymmetric Antibodies : There is a population of antibodies which, owing to the presence of a mannose-rich oligosaccharide residue on one of the Fab arms of the molecule, possess an asymmetric structure. Due to the asymmetric structure these molecules have no effector functions and may act as blocking antibodies. Interestingly, asymmetric antibodies, which do not