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How does implantation attach a blastocyst to the uterine wall?

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A series of medical illustrations showing the stages of childbirth: the baby's position at the onset of labor, flexion, internal rotation of the head, extension, external rotation of the head, and the uterus immediately after birth with the placenta and umbilical cord. — birth Sequential changes in the position of the child during labour.

Implantation is the process by which a blastocyst attaches to and embeds within the endometrium, the lining of the uterus. This process relies on the prior preparation of the uterine wall by the hormone progesterone, which increases blood supply and nutrient secretions to create a receptive environment.312

Six to 10 days after fertilization, the blastocyst adheres to the uterine lining. Once contact is established, the trophoblast—the outer layer of the blastocyst—exerts an enzymic, destructive influence on the endometrium. This action erodes the superficial epithelium and deeper connective tissue, allowing the blastocyst to actively burrow into the uterine wall.243

As it embeds, the trophoblast proliferates to form a syncytial layer that continues to erode maternal tissue and tap into uterine capillaries. This invasive process ensures the developing embryo establishes a physiological connection with the mother, eventually leading to the formation of the placenta.42