Question

Identify the trophoblast cells which are in contact with embryonal knob during blastulation.

Hint:

Cells of Rauber degenerate later, allowing direct contact between cytotrophoblast and ICM during implantation.

Answer 1

During blastulation in mammals, the blastocyst forms with an outer trophoblast layer and inner embryonal knob (inner cell mass, ICM). The trophoblast cells directly contacting the embryonal knob are the cells of Rauber (Rauber's cells), which are flattened and lie between the trophoblast and ICM at the embryonic pole.