Question

In an embryonic vertebrate, the apical ectodermal ridge (AER) is a thickened area at the tip of the bud. The cells of the AER secrete protein signals that promote limb-bud outgrowth, and removing the AER blocks growth of the limb along the proximal–distal axis. How would the forelimb of an embryo develop if the AER was removed early or late in limb development?

Answer 1

Step-by-step explanation:

The Removal of the AER results in the cessation of limb bud out-growth and a truncated proximal–distal (PD) axis

The earlier the AER is removed, the more truncated the resulting limb is, with only the very proximal structures (humerus) forming

The later the AER is removed, the less truncated the resulting limb is, with the more distal structures forming (humerus and radius/ulna)

Which is a process

Called Zone model