BIO380H5 Lecture Notes - Lecture 12: Gestational Sac, Cytotrophoblast, Decidua
Document Summary
Implantation occurs during the first week of development (6-7 days) The embryo acts as a parasite that grows in the uterine cavity. There are two types of tissue: the extraembryonic tissue that is derived from the inner cell mass; it consists of . Extraembryonic mesoderm will form majority of the umbilical cord: the tissues derived from the trophoblast. Any cells derived from the trophoblast will make the placenta. In between the inner cell mass and the outer cell mass we have a space called the extraembryonic coelom. As the embryo grows larger the extraembryonic coelom (chorionic cavity) decreases, since it is grown within the coelom. The extraembryonic mesoderm separates the growing embryo from the trophoblasts. The small amniotic cavity will eventually grow larger and cover the entire embryo, thus the only connect between the inner cell mass and the extraembryonic mesoderm is the body stalk.
