Where does implantation occur in the female reproductive system?

The process of implantation in humans occurs within the female reproductive system, specifically in the uterus. After fertilization of an egg by a sperm, the resulting zygote undergoes cell divisions and develops into a hollow ball of cells called a blastocyst. The blastocyst then travels through the fallopian tube and enters the uterus. Within the uterus, the blastocyst finds a suitable location and undergoes the process of implantation.

During implantation, the outer layer of cells in the blastocyst, known as the trophoblast, attaches itself to the inner lining of the uterus, called the endometrium. This attachment involves the erosion of the uterine lining and the formation of blood vessels that connect the blastocyst to the maternal circulatory system. Through these blood vessels, the developing embryo begins to receive oxygen and nutrients from the mother's bloodstream.

Implantation usually takes place 6 to 12 days after ovulation. Once the blastocyst has successfully implanted, the endometrium continues to thicken and develop to support the growth and development of the embryo during the early stages of pregnancy.