What does the trophoblast develop into during pregnancy?

The trophoblast is a key structure that arises from the outer layer of cells of a blastocyst in early pregnancy. Its primary role is to facilitate the implantation of the embryo into the uterine wall and to participate in the formation of the placenta. During the process of implantation, the trophoblast differentiates and proliferates, forming structures that will become an integral part of the placenta.

The placenta itself is critical for the exchange of nutrients, gases, and waste products between the mother and the developing fetus. It acts as an endocrine organ, producing hormones that are vital for the maintenance of pregnancy. The trophoblast develops into both the cytotrophoblast and the syncytiotrophoblast, which contribute to the placental structure and function.

While other options listed might seem relevant in the context of pregnancy, they do not directly stem from the trophoblast. The embryonic disc develops later from other cells in the blastocyst, the amniotic sac forms from ectodermal cells and is a separate structure surrounding the embryo, and chorionic villi are extensions of the trophoblast but are not the end product itself. Thus, the placenta is the correct developmental outcome of the trophoblast during pregnancy.