Separation of the embryonic digits depends on which molecular process operating in the interdigital mesenchyme?
- A BMP-mediated programmed cell death ✓
- B FGF-driven proliferation along the proximodistal axis
- C SHH-dependent recruitment of myogenic precursors
- D Wnt7a-directed dorsoventral specification
Correct answer: A. BMP-mediated programmed cell death
Explanation
Interdigital tissue is removed by apoptosis triggered by BMP signalling from the interdigital mesenchyme itself; experimental addition of BMP antagonists such as noggin preserves webs, producing syndactyly, as seen in some genetic forms. FGF from the AER promotes outgrowth and actually opposes interdigital apoptosis, which is why the other options cannot explain digital separation.
Reference: Langman's Medical Embryology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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