Final answer:
Gestational trophoblastic neoplasms are tumors that develop from the trophoblast and exhibit fetal cell characteristics.
Step-by-step explanation:
Tumors that arise from the trophoblast, the outer layer of a blastocyst that implants in the uterus, are known as gestational trophoblastic neoplasms. The primary feature of gestational trophoblastic neoplasms is the way the tumor cells behave—they behave more like fetal cells than adult cells. Fast mitosis, the reexpression of fetal antigens, and the creation of isoenzymes unique to fetal cells—which are absent in adult cells—are the results of this. For instance, carcinomas have a kind of alkaline phosphatase that is placental in origin. By creating the syncytiotrophoblast and secreting human beta chorionic gonadotropin (hCG) to preserve the corpus luteum and high progesterone levels—both necessary for a favorable environment for the growing embryo—the trophoblast itself performs a critical role during implantation.