<prompt> Continued production of estrogen and progesterone from the corpus luteum of the ovary is essential during the implantation process. The corpus luteum of the ovary now known as the corpus luteum of pregnancy is maintained by the secretion of human chorionic gonadotropin from which source?The embryoblast cellsThe endometrial glandsThe hypoblast cellsThe trophoblast cells  <response>: Human chorionic gonadotropin is produced by the cells of the trophoblast cells, which blocks the degeneration of the corpus luteum, allowing it to continue to produce steroids essential to facilitate the implantation process in the uterine endometrium, at least for the first 10-12 weeks of embryonic development. The embryoblast cells subsequently divide to form a bilaminar germ disc consisting of the hypoblast endoderm and epiblast ectoderm. Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. 2010. Chapter 3. Implantation, Embryogenesis, and Placental Development. In F.G. Cunningham, K.J. Leveno, S.L. Bloom, J.C. Hauth, D.J. Rouse, C.Y. Spong Eds, Williams Obstetrics, 23e. 