AP PSYCHOLOGY

Detailed explanation-1: -Trophoblasts (from Greek to feed: threphein) are cells forming the outer layer of a blastocyst, which provides nutrients to the embryo, and develops into a large part of the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg.

Detailed explanation-2: -The appearance of a fluid-filled inner cavity marks the transition from morula to blastocyst and is accompanied by cellular differentiation: the surface cells become the trophoblast (and give rise to extraembryonic structures, including the placenta) and the inner cell mass gives rise to the embryo.

Detailed explanation-3: -Trophoblast is not directlty involved in the formation of embryo. The inner cell mass is involved in the formation of embryo.

Detailed explanation-4: -Trophoblast (derived from the Greek word ‘tropho, ’ meaning to feed) is the epithelial cell in the placenta, a transient organ which plays a pivotal role in fetal growth and development during pregnancy.