epiblastceller

Epiblast cells, or epiblastceller in some languages, are the cells of the epiblast, the upper layer of the bilaminar embryonic disc formed from the inner cell mass of the mammalian blastocyst. The opposing layer is the hypoblast (primitive endoderm). The epiblast faces the amniotic cavity, while the hypoblast lines the yolk sac. Epiblast cells are pluripotent, capable of giving rise to all embryonic tissues and, in many species, contribute to some extraembryonic structures such as the amnion.

During gastrulation, epiblast cells undergo an epithelial-to-mesenchymal transition, migrate toward and through the primitive streak, and differentiate into the three germ layers: ectoderm, mesoderm, and endoderm. This establishes the embryo proper and sets up the body plan. In humans and other mammals, formation of the amnion largely involves epiblast-derived cells that spread to envelop the embryo and form the amniotic cavity; later, some epiblast-derived cells contribute to extraembryonic mesoderm.

Molecularly, epiblast cells express pluripotency-associated transcription factors such as Oct4, Sox2, and Nanog, which are gradually downregulated as differentiation proceeds. The study of epiblast cells is central to developmental biology and stem cell research, as embryonic stem cells are typically derived from the post-implantation epiblast and retain pluripotency.

Disruptions in epiblast formation or function can lead to early developmental abnormalities or loss.