| Division of the human zygote leads to the formation of the blastocyst that contains human embryonic stem cells (hESC) which develop into the embryo. Little is known about the physiological signals that direct hESC division and differentiation during early embryogenesis. A number of growth factors, including the pregnancy-associated hormone human chorionic gonadotropin (hCG), are secreted by trophoblasts^1-3^ that lie adjacent to the embryoblast in the blastocyst, but it is not known whether these growth factors directly signal the epiblast. Here we show that hCG promotes the division of embryoblast-derived inner mass cells (hESC), and their differentiation during blastulation and neurulation. Inhibition of LH/hCG receptor (LHCGR) signaling with... |
