Question

How does implantation of an embryo occur in a human female?

Answer 1

Implantation is the process of attachment and invasion of the endometrium by blastocysts. In humans, this process begins at the end of the first week; the most successful pregnancy in humans is childbirth 8-10 days after ovulation. The Implantation process continues in the second week of development.

Complete answer:
Let’s first all understand about implantation.
Each of the 64 cells of a blastocyst is arranged in the form of an inner or outer cell. The outer cells form the periphery of the zygote and are called trophoblasts. The inner cells clump together and become the inner cell mass or ICM. ICM develops within the embryo.
The blastocyst is completely immersed in the endometrium. Blastocysts form villi, tightly contacting the wall of the uterus. The blastocyst receives food and parasitizes in the womb. The chorionic membrane is an additional embryonic membrane arising from the trophoblast. It secretes a hormone called human chorionic gonadotropin, which supports the corpus luteum and stimulates its release of progesterone.
The trophoblast secretes enzymes or fluids that are completely absorbed by the cells of the uterus, allowing blastocysts to penetrate the walls of the uterus. It might sound a little odd, but believe it or not, my mom didn't feel anything.
During transplantation, trophoblast cells secrete a hormone called human chorionic gonadotropin (HCG). HCG helps maintain pregnancy while the placenta takes over.

Note:
HCG helps to maintain pregnancy while the placenta takes over. Therefore, its value is highest when the woman is pregnant. This is what a pregnancy test kit is looking for. Detectable HCG levels can be found in urine or blood, so urine and blood test strips can be used to confirm pregnancy. In many mammalian species, embryo implantation and early pregnancy occur in a hypoxic environment.