The structure in birds and placental mammals that is most equivalent to the dorsal lip of the frog blastopore is
A) the primitive groove.
B) the archenteron.
C) the yolk plug.
D) Hensen's node.
E) the epiblast.

Question

Quizplus · Accepted Answer

Hensen's node is the region at the anterior end of the primitive streak in birds and placental mammals that is equivalent to the dorsal lip of the frog blastopore. It plays a key role in organizing the developing embryo's body plan. The primitive groove (A) is a narrow, longitudinal depression on the surface of the embryo where cells migrate during gastrulation. The archenteron (B) is the primitive gut that forms during gastrulation. The yolk plug (C) is a mass of yolk in the center of the frog blastula that is surrounded by the vegetal pole. The epiblast (E) is the outer layer of cells in the early embryo.

The Structure in Birds and Placental Mammals That Is Most