implantation of the blastocyst takes place in the endometrium.
implantation of the blastocyst takes place in the endometrium.
where does implantation of the blastocyst take place?
the endometrium
implantation is critical to the survival and development of the early human embryo. it establishes a connection between the mother and the early embryo which will continue through the remainder of the pregnancy. implantation is made possible through structural changes in both the blastocyst and endometrial wall. the zona pellucida surrounding the blastocyst breaches, referred to as hatching. this removes the constraint on the physical size of the embryonic mass and exposes the outer cells of the blastocyst to the interior of the uterus. furthermore, hormonal changes in the mother, specifically a peak in luteinizing hormone (lh), prepare the endometrium to receive and envelop the blastocyst. the immune system is also modulated to allow for the invasion of the foreign embryonic cells. once bound to the extracellular matrix of the endometrium, trophoblast cells secrete enzymes and other factors to embed the blastocyst into the uterine wall. the enzymes released degrade the endometrial lining, while autocrine growth factors such as human chorionic gonadotropin (hcg) and insulin-like growth factor (igf) allow the blastocyst to further invade the endometrium.
blastocyst
embryonic stem cell









































embryonic stem cells (es cells or escs) are pluripotent stem cells derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo. human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells. isolating the embryoblast, or inner cell mass (icm) results in destruction of the blastocyst, a process which raises ethical issues, including whether or not embryos at the pre-implantation stage should have the same moral considerations as embryos in the post-implantation stage of development.
embryonic stem cell