Which of the following cells are responsible for myelination in Central Nervous System?
Ans. d (Oligodendrocytes). (Ref. Human Histology by JB Singh, 3rd ed., p 12\37, 165)Myelin sheaths are produced by oligodendrocytes in CNS and schwann cells in peripheral nerves.# Microglial cells are supporting cells of CNS and are Part of Macrophage system (Gitter cells).# Conduction velocity is greatly increased in myelinated, as opposed to unmyelinated nerves.# Oligodendrocytes wrap their plasma membranes round and round the axons to produce a sheath of tightly stacked bilipid layer.# This myelin is not continuous and there are gaps in the sheath called nodes of Ranvier.# Astrocytes by their foot processess help in forming blood-brain barrier.# Ependymal cells line ventricles, are tall columnar cells with fine cilia and secrete CSF in small amount.# Modified ependymal cells having long protoplasmic processes are called tanycytes.Educational points:# Neural crest derivatives:- ANS,- Chromaffin cells of adrenal medulla,- Celiac ganglion,- Parafollicular (C) cells of thyroid,- Dorsal root ganglia,- Enterochromaffin cells,- Schwann cells,- Laryngeal cartilage,- Melanocytes,- Pia and arachnoid,- Odontoblasts,- Bones of the skull.
Astrocytes
Schwann cells
Microglial cells
Oligodendrocytes
Neuroanatomy