A newborn girl has a large tumour arising from the coccyx that histologically contains skin, cartilage, gut epithelium and thyroid tissue. This sacrococcygeal teratoma is believed to arise from remnants of which embryological structure?
- A Neural crest cells
- B Notochord
- C Primitive streak ✓
- D Cloacal membrane
Correct answer: C. Primitive streak
Explanation
The primitive streak normally regresses and disappears by the end of the fourth week. Persisting multipotent primitive streak cells at the caudal end retain the ability to differentiate into tissues of all three germ layers, giving rise to sacrococcygeal teratomas, the commonest neonatal tumour. Notochord remnants give chordomas in later life, and the cloacal membrane does not contain pluripotent cells capable of forming all three germ layers.
Reference: Moore and Persaud, The Developing Human, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.