Which molecule primarily ventralizes the neural tube to establish ventral identities?

Which molecule primarily ventralizes the neural tube to establish ventral identities?

• A. BMP
• B. WNT
• C. SHH
• D. FGF

Answer: (C)

Sonic Hedgehog is the ventralizing morphogen that patterns the neural tube along the bottom-to-top axis. It is secreted by the notochord and the floor plate, creating a concentration gradient with the highest levels ventrally. Cells read this SHH signal and adopt specific ventral identities depending on the local amount of SHH they experience. That ventral gradient drives the formation of ventral progenitor domains and motor neuron programs; for example, high SHH promotes ventral identities in the neural tube and induces transcription factors that specify motor neuron fates. BMPs and WNTs come from the dorsal side and establish dorsal identities, opposing the ventral pattern, so they’re responsible for dorsal structures rather than ventral ones. FGFs have various roles in neural development, including influence on progenitor proliferation and patterning, but they are not the primary signal that ventralizes the neural tube.

Sonic Hedgehog is the ventralizing morphogen that patterns the neural tube along the bottom-to-top axis. It is secreted by the notochord and the floor plate, creating a concentration gradient with the highest levels ventrally. Cells read this SHH signal and adopt specific ventral identities depending on the local amount of SHH they experience. That ventral gradient drives the formation of ventral progenitor domains and motor neuron programs; for example, high SHH promotes ventral identities in the neural tube and induces transcription factors that specify motor neuron fates.

BMPs and WNTs come from the dorsal side and establish dorsal identities, opposing the ventral pattern, so they’re responsible for dorsal structures rather than ventral ones. FGFs have various roles in neural development, including influence on progenitor proliferation and patterning, but they are not the primary signal that ventralizes the neural tube.