The apical ectodermal ridge
A)forms at the proximal end of each limb bud.
B)plays a role in differentiation and elongation of the limb.
C)ossifies prior to formation of the hand and foot plates.
D)must undergo apoptosis before the limb can develop.
E)secretes mesoderm for muscle formation.

Question

Quizplus · Accepted Answer

The apical ectodermal ridge (AER) is a structure that forms at the distal end of each limb bud and plays a critical role in limb development. It is responsible for the differentiation and elongation of the limb, as well as the formation of the hand and foot plates. The AER secretes signaling molecules that direct the underlying mesoderm to form specific structures such as bones, muscles, and tendons. Without the AER, limb development is severely compromised, and the limb may not form correctly. Therefore, choice B is correct.

The Apical Ectodermal Ridge