Vegetal pole

In developmental biology, the term vegetal pole refers to the lower hemisphere of a blastula embryo (as it is conventionally drawn, in reality the vegetal pole may not be the lower hemisphere). The vegetal pole contains large yolky cells that divide very slowly, in contrast with the animal pole above it. The vegetal pole draws its name from its inactivity relative to the lively animal pole. In some cases, the vegetal pole is thought to differentiate into the extraembryonic membranes that protect and nourish the developing embryo, such as the placenta in mammals and the chorion in birds.