The document discusses the different types of neuroglia, or non-neuronal cells, in the central and peripheral nervous systems. It describes six main types of neuroglia: oligodendrocytes that produce myelin in the CNS, astrocytes that support neurons structurally and metabolically, ependymal cells that line ventricles, microglia that perform immune functions, Schwann cells that myelinate nerves in the PNS, and satellite cells that cover neuronal cell bodies in ganglia. Neuroglia outnumber neurons 10:1 and play crucial roles in insulation, support, repair and immune defense of the nervous system.

1. Neuroglia: Non-Neuronal Cells
of the Nervous System

2. Plan
 Overview of Neuroglia
 In detail
 Big picture

3. Overview
Glial Cells & Neuronal Activity
 Glial cells are 10 times more abundant in the mammalian brain than
neurons.
 In the CNS glial cells surround most of the neurons
 Glial cells furnish a microenvironment ideal for neuronal activity.
 They are six and will be discussed in the following slides.

4. 1) Oligodendrocytes
 Oligodendrocytes (Gr. oligos, small,
few + dendron, tree + kytos, cell)
 Produce myelin sheath through
their extensive processes
 Predominately existent in white
matter.
 Their processes is not visible by light
staining microscope.
2) Astrocytes
Astrocytes (Gr. astron, star, + kytos)
fibrous astrocytes relatively few long
processes are located in the white matter.
protoplasmic astrocytes, with many short,
branched processes, are found in the gray
matter.
1) Support neurons
2) Very important in early development
3) They form perivascular feet
4) They form Glial limiting membrane
5) Glial fibrillary acid protein (GFAP) is an
important marker
In detail

5. (a): X500. Gold chloride.
Cytoplasmic processes (P)
cell body or soma (S).
Morphological y:
fibrous (relatively few and straight processes)
protoplasmic (numerous branching processes
(b): X500. Anti-GFAP immunoperoxidase and
hematoxylin counterstain.
fibrous astrocyte (A) and its processes. perivascular
feet (PF) at the ends of numerous astrocytic
processes.

7. 3) Ependymal Cells
low columnar or cuboidal cells.
1. Lining ventricles and spinal cord
2. Cillia for (CSF).
3. Other times microvilli for absorption
4. Joined apically by junctional complexes
like epithelia
5. No basal lamina but extend to neuropil
4) Microglia
are small cells with short irregular
processes
1. Migrate to neuropil to analyse and
the area
2. Major mechanism of defence for CNS.
3. Their origin is not neural tube, but
from circulating monocytes in blood.

8. Ependymal cells
epithelial-like cells that form a single layer lining the fluid-filled ventricles of
(a) the cerebrum (b) the central canal of the spinal cord.

9. 5) Schwann cells
also called neurolemmocytes,
Have trophic interactions with neurons.
One neurolemmocyte forms myelin
around a segment of one axon
6) Satellite Cells of Ganglia
Form a covering layer over the large
neuronal cell bodies in PNS ganglia.
trophic or supportive role, but the
molecular basis of their support is poorly
understood.

10. Big Picture
Glial Cell Type Origin Location Main Functions
Oligodendrocyte Neural tube Central nervous system Myelin production, electric insulation
Neurolemmocyte Neural crest Peripheral nerves Myelin production, electric insulation
Astrocyte Neural tube Central nervous system Structural support, repair processes
Blood-brain barrier, metabolic exchanges
Ependymal cell Neural tube Central nervous system Lining cavities of central nervous system
Microglia Bone marrow Central nervous system Immune-related activity

11. Glial cell in the CNS:
(a): Oligodendrocytes
myelinate parts of several axons.
(b): Astrocytes
have multiple processes and form perivascular
feet that completely enclose all capillaries
(only a few such feet are shown here to allow
their morphology to be seen).

12. (c): Ependymal cells
are epithelial-like cells that line the
ventricles and central canal.
(d): Microglial cells have a protective,
phagocytic, immune-related function. Glial
cells in the PNS.

13. Glial cells in the PNS:
(e): Neurolemmocytes:
commonly called Schwann cells, form a series
enclosing axons.
(f): Satellite cells
are restricted to ganglia where
they cover and support the large neuronal cell
bodies.

14. References
 Fundemental Neuroscience for Basic and Clinical Applications, 3rd Ed
 Color Textbook of Histology
 Janguira’s Basic Histology, 12th Ed

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16. (a): . X200. H&E.
(b): X200. Gold & hematoxylin.

17. Glia Limitans
Neuropil
Red arrow = pia mater cell; GL = glia limitans

18. Quiescent Microglia: Stained with silver