Enzymes are secreted from the cells of trophoblast.

Enzymes are secreted from trophoblast cells that digest some tissues and blood vessesls of the wall of uterus and makes implantation possible. The inner wall of uterus develops and surrounds the embryo partially. This process is called implanation. Thus for implantation, to fix embryo to the wall of uterus, some part of the wall of uterus is to be digested. It is done by enzymes.