Implantation

Implantation : It is the process by which the blastocyst, after its formation, becomes embedded within the endometrium of the uterus. This process usually begins on day 7 after fertilization, and by the end of day 10 the embryo is completely buried within the endometrium — typically implanting in the region of the uterine fundus. In this process, the embryo attaches itself, at its embryonic pole, close to the endometrium; the trophoblast cells at this pole have the ability to stick to the uterine wall. Rapid division of the trophoblast cells lying against the embryonal knob produces two distinct layers: an outer syncytiotrophoblast, a syncytium (a layer of protoplasm containing many nuclei) that sends out processes invading the endometrium extensively, and an inner cytotrophoblast, whose cells retain their individual cell boundaries. Lytic enzymes secreted by the trophoblast rupture endometrial c …