Extraembryonic Tissues: Essential for Embryonic Development and Survival

Extraembryonic tissues are tissues that develop outside of the embryo proper, but are essential for its development and survival. These tissues include the placenta, the yolk sac, and the amniotic membrane.

The placenta is a disk-like organ that forms from the fusion of trophoblast cells and cytotrophoblast cells. It provides oxygen and nutrients to the developing embryo, and also removes waste products. The yolk sac is a structure that surrounds the embryo and provides it with nutrients and protection. The amniotic membrane is a thin layer of tissue that surrounds the embryo and the yolk sac, and helps to maintain the proper environment for development.

All of these extraembryonic tissues are important for the survival and development of the embryo, and they play a crucial role in the early stages of pregnancy.