Embryoimplantaatio

Embryoimplantaatio, also known as implantation, is a crucial step in pregnancy. It refers to the process by which a developing embryo attaches to and burrows into the uterine lining, called the endometrium. This event typically occurs about six to twelve days after fertilization.

The journey begins after fertilization, where a zygote forms and undergoes rapid cell division as it travels down the fallopian tube towards the uterus. By the time it reaches the uterus, it has developed into a blastocyst, a hollow ball of cells containing an inner cell mass that will develop into the fetus and an outer layer called the trophectoderm, which will contribute to the placenta.

Upon reaching the endometrium, the blastocyst must find a receptive site. The uterine lining, which has been prepared by hormonal changes during the menstrual cycle, is thick and rich in blood vessels. The trophectoderm of the blastocyst secretes enzymes that help it to break down a small portion of the endometrium, allowing the blastocyst to embed itself. This initial attachment and invasion are critical for establishing a successful pregnancy.

Once implanted, the developing embryo begins to receive nourishment from the maternal blood supply through the developing placenta. This marks the transition from a free-floating structure to a more integrated part of the maternal system. If implantation fails, the uterine lining sheds, resulting in menstruation, and a pregnancy does not continue.