6. lecture on the histology of peripheral nerve and ganglia by dr. roomi

7/31/2019 6. Lecture on the Histology of Peripheral Nerve and Ganglia by Dr. Roomi

1/15


2/15

peripheral nerve

Peripheral nerves include: cranial

nerves, spinal nerves.

It is made up of bundle of nerve

fibers, both myelinated and

unmyelinated.

On naked eye examination, it

appears whitish and glistening

because of their myelin and

collagen content.

Examples: median nerve, ulnarnerve, sciatic nerve


3/15

peripheral nerve (cont.)

Epineurium: it is sheath of dense

irregular C.T. around peripheral

nerve.

Perineuriun:

it is C.T sheath around each fascicle

or bundle of nerve fibers.

This is made by many concentric

layers of epitheloid cells joined

together by tight junctions .

Perineurium acts as a barrier to the

passage of materials.

endoneurium: it is thin layer of

C.T. around each nerve fiber. It is

composed of delicate collagenous

and reticular fibers and

fibroblasts.


4/15

peripheral nerve (l.s.)


5/15


6/15

peripheral nerve- identification points

Bundles of nervefibers

Myelin sheath isseen as unstainedarea

Endoneurium,perineurium andepineurium isvisible


7/15

GANGLIA

Ganglia: It is collection ofnerve cell bodies outside theCNS

Ganglia are ovoid structuresassociated with peripheralnerve.

microsopically and functionallythe ganglia are of two types: Craniospinal (sensory) ganglia

Autonomic ganglia Common features of both

types of ganglia: Both types of ganglia have C.T.

capsule.

The body of each ganglion cellis surrounded by satellite cells


8/15

Cranio Spinalganglia

Cranial ganglia

Spinal ganlia (dorsal root ganglia)

C.T. Capsule

Ganglion cells are pseudounipolarneurons ***

Each cell has a single process whichbifurcates in a T-shaped manner.

One of the two processes acts asdendrite and passes to peripheryto terminate at a receptor organ

The othe branch acts as axon andpasses to CNS.

The nerve impulses pass from theperiphery to CNS, bypassing thecell body.

So the cell body form no synapsesand performs an exclusivelytrophic function.


9/15

Cranio Spinal ganglia (cont.)

The nerve cell bodies arearranged as groups in theperipheral zone of theganglion.

Each ganglion cell issurrounded by a singlelayer of low cuboidal cellsare called as satellite cells

Central zone of the

sensory ganglion showsgreat predominance ofnerve fibers


10/15

Dorsal root ganglion


11/15


12/15

Dorsal root ganglion- how to draw it!


13/15

Autonomic Ganglia

These ganglia areassociated withsympathetic andparasympathetic ANS.

These ganglia containmultipolar neurons: Each ganglion cell has

many dendrites and asingle axon.

Dendrites receive synapsesfrom the incomingpreganglionic nerve fibers

Axon passes out aspostganglionic fiber.


14/15


15/15

Ganglia

Cranio Spinal Autonomic

Cranial nerve ganglia Spinal ganglia Sympathetic Parasympathetic

Cranio Spinal ganglia Autonomic ganglia

ganlionic cells are present as groupsin the ganglion.

Variable size of the ganglion cells

Pseudo unipolar cells

Sensory

No synapse

+++ satellite cells

complete capsule of satellite cells

Evenly distributed

Uniform size Multipolar cells

Secretomotor

++ synapse

+ satellite cells

incomplete capsule of satellite cells

6. lecture on the histology of peripheral nerve and ganglia by dr. roomi

Documents