The fetal pole appears as a thick area alongside the yolk sac, which is a source of nourishment at the beginning of pregnancy. It's a preliminary structure that ultimately develops into a fetus.

The fetal membranes consist of the chorion, amnion, yolk sac, and allantois. The chorion has three layers: cytotrophoblastic, chorionic connective tissue, and basement membrane. The chorion lies ...

or fetal tissue, and the hypoblast, or the yolk sac. When they tracked GFP expression, the team found that one population of cells dominated in either the ICM or the TE, but that this imbalance was ...

The marsupials have a yolk sac placenta (the initial stage in the development of the placenta in placental mammals. In placental mammals, the chorion and the allantois together form the fetal side of ...

CRL: Crown—rump length; EV: Embryo volume; FV: Fetal volume; GSV ... the placenta (PV), embryo (EV), fetus (FV), gestational sac and yolk sac. PV, EV/FV ratio and gestational sac volume are ...