During vertebral column formation, the notochord and ventral neural tube secrete SHH, which induces the ventromedial part of each somite to differentiate and express the transcription factor PAX1. Which somite compartment is being induced?
- A Sclerotome ✓
- B Dermomyotome
- C Myotome
- D Syndetome
Correct answer: A. Sclerotome
Explanation
SHH from the notochord and floor plate induces the ventromedial somite cells to undergo epithelial-mesenchymal transition and form the sclerotome, marked by PAX1 expression. Sclerotome cells surround the notochord and neural tube to form vertebral bodies and intervertebral discs. Myotome formation is driven mainly by Wnts from the dorsal neural tube and ectoderm, the dermomyotome forms under Wnt plus BMP influence dorsally, and the syndetome gives rise to tendons under FGF signalling from myotomes.
Reference: Langman's Medical Embryology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.