If the apical ectodermal ridge is surgically removed from an embryo, it will lose
A) positional information for limb-bud pattern formation.
B) guidance signals needed for correct gastrulation.
C) unequal cytokinesis of blastomeres.
D) the developmental substrate for the gonads.
E) the developmental substrate for the kidneys.

Question

Quizplus · Accepted Answer

The apical ectodermal ridge (AER) is a thickened region of ectoderm at the distal end of the developing limb bud that provides positional information for limb-bud pattern formation. If it is surgically removed, the limb bud development will be disrupted, and the resulting limb will be malformed or absent. The AER is not involved in guidance signals for gastrulation, cytokinesis of blastomeres, or the development of the gonads or kidneys.

If the Apical Ectodermal Ridge Is Surgically Removed from an Embryo