Limb Development

Question 1

describe the structure of the early limb bud

Answer 1

consists of an ectodermal epithelial jacket surrounded by a mesenchymal core of loosely packed mesenchymal cells

dorsal tip of limb bud has a specialised structure - apical ectodermal ridge/AER
- composed of pseudostratified epithelial cells

Question 2

what structure is at the dorsal tip of the limb bud? where does it arise from?

Answer 2

apical ectodermal ridge/ AER - composed of pseudostratified epithelial cells

arises from the distal ectoderm & physically marks the boundary between dorsal and ventral surfaces

Question 3

what is the importance of the ZPA as a signalling centre in limb development?

Answer 3

ZPA tissue provides important signals that establish limb patterning along the AP axis

Question 4

what is the importance of the AER as a signalling centre in limb development?

Answer 4

provides signals for PD axis limb growth (formation & continued growth)

AER removal = truncated limbs, lost distal structures