The Spemann-Mangold organiser induces neural tissue in the overlying ectoderm primarily through secretion of molecules belonging to which functional class?

• A Antagonists of bone morphogenetic protein signalling ✓
• B Agonists of sonic hedgehog signalling
• C Activators of the fibroblast growth factor receptor
• D Secreted ligands of the Notch pathway

Explanation

According to the default model of neural induction, ectoderm becomes neural when BMP signalling is suppressed. The organiser secretes the BMP antagonists noggin, chordin and follistatin, allowing endogenous neural determinants to act. SHH acts later to pattern the ventral neural tube, and FGF functions as a posteriorising signal, so neither explains primary induction.

Reference: Moore and Persaud, The Developing Human, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.