Trophoblast cells in contact with the embryonal knob are called...

The blastocyst consists of an outer layer of cells called the trophoblast and an inner group of cells called the inner cell mass or embryonal knob.

The specific trophoblast cells that are in direct contact with the embryonal knob are known as the cells of Rauber.

These cells eventually degenerate, allowing the inner cell mass to be exposed and participate in the formation of the embryonic disc.

Answer: cells of Rauber