microscopic anatomy of nervous system

Peripheral nerves

• Are composed of bundles of nerve fibers held together by connective tissue and a specialized layer of cells, the perineurium.

• The connective tissue consists of a outer layer, the epineurium, surrounding the whole nerve,

the perineurium, surrounding the bundles of nerve fibers, and

the endoneurium associated with individual nerve fibers

Peripheral nerve

Axon

Myelin space

Schwaan cell nucleus

Cross section of a thick nerve showing the epineurium, perineurium, and endoneurium. The myelin sheath that envelops each axon was partially removed by the histologic technique.

Cerebrum

• This micrograph shows a low-magnification view of the cerebral cortex. It includes the full thickness of the grey matter and a small amount of white matter at the bottom of the micrograph.

There are six layers in the cerebral cortex• i) the plexiform layer: consists largely of fibers, most of

which travel parallel to the surface and relatively few cells, mostly neuroglial cells and occasional horizontal cells of Cajal.

• ii) the outer granular layer: consists small pyramidal cells, granule cells and stellate cells

• iii) the outer pyramidal cells layer : contain medium pyramidal cells

• iv) inner granular layer: contain many small granular cells

• v) inner pyramidal cells layer • vi) the polymorphic cells

layer

Cerebellum

• It consists of a core of white matter and the superficially located gray matter. The grey matter is subdivided into three layers,

1. the outer molecular layer,2. a middle Purkinje cell layer3. and the inner granular layer

1. The outer molecular layer:

contains relatively few neurons (stellate and basket cells) and large numbers of unmyelinated fibers .

2. A middle Purkinje cell layer:

the Purkinje cells have very large cell bodies, a relatively fine axon extending through the granular cell layer and an extensively branching dendritic system which arborises into the outer molecular layer

3. The inner granular layer:

contains numerous small neurons , the non-myelinated axons. It also contain golgi cells scattered in the superficial part of the granular cell layer

Cerebellum

• White matter

• Gray matter

Cerebellum

1.the outer molecular layer,

2. a middle Purkinje cell layer

3. the inner granular layer

Cerebellum