Q.95. Which ONE of the following glial cells is NOT derived from the ectoderm?
(A) Astrocytes
(B) Microglial cells
(C) Oligodendrocytes
(D) Ependyma
Microglial cells are the glial cells not derived from the ectoderm. They originate from mesoderm, unlike other CNS glia.
Correct Answer
** (B) Microglial cells **
This multiple-choice question tests knowledge of glial cell embryological origins in neurobiology, a key topic in molecular biology and neuroscience for exams like NEET or university courses.
Ectoderm-Derived Glia
Astrocytes support neurons by maintaining the blood-brain barrier and regulating ions. They arise from neuroectoderm during CNS development.
Oligodendrocytes produce myelin sheaths around CNS axons, derived from ventral neural tube regions like the ventricular zone.
Ependyma line brain ventricles and spinal canal, producing cerebrospinal fluid; these cells stem from ectodermal neuroepithelium.
Microglia Origin
Microglial cells act as immune defenders in the CNS, phagocytosing debris. Unlike other options, they derive from mesodermal yolk sac precursors that migrate into the brain.
| Glial Cell | Germ Layer Origin | Key Function |
|---|---|---|
| Astrocytes | Ectoderm | Structural support, BBB maintenance |
| Microglial cells | Mesoderm | Immune response, phagocytosis |
| Oligodendrocytes | Ectoderm | Myelin production in CNS |
| Ependyma | Ectoderm | CSF production, ventricle lining |
