introduction the neurons of the cerebral cortex study methodology laminae (layers)

HISTOLOGY OF THE CEREBRAL CORTEX

Introduction The neurons of the cerebral cortex Study methodology Laminae (layers)

Hemisphere(s) surface (cerebral cortex) is called pallium having variable depth/thickness (15–45mm) from one area to another.- thicker in the summit of the gyli, and thinner on the

depth of the sulci.

The pallium has laminar (layers) arrangement which associate with blood vessels – angioarchtecture.

Neurons are forming a microarchtecture by presenting different types of cell morphologies

These morphologies are i. Pyramidal cells ii. Non-pyramidal cells called stellate or granule cells

- They are spiny or non-spiny.

Cerebral cortex

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Cells are also subdivided basing on their sizes, shapes and neuritic arrays.

Cont……..

Cerbral hemisphere showing the relationship between pallium and sulcus .

Cerebral cx cont….

This section is showing cells in different orientation as they are seen in the neuropil.

Cont………..

1. Pyramidal cell: This is a flask-shaped or triangular cell body with single apical or multiple basal dendrities.

- Form most of the majority of projection neurons.

2. Spiny stellate cells: most of these are multipolar cells. - Numerous in the lamina IV. - They have relatively small sized cell bodies and spiny dendrites. - Their axons ramify within the gray matter in a vertical plane.

3. Non spiny stellate cells: These are numerous group of interneurons (association neurons). - They have different shapes like basket, chandelier, double bouquet, neuroglial forms bipolar or fusiform and horizontal cells.

THE CELLS

Pyramidal cells

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This is a histological slide of the cerebrum. Numerous pyramidal shaped neurons are present within perineuronal spaces. These cells have large vesicular nuclei. The small cells seen only as nuclei are glial cells. The stringy pink background is the neuropil. At high power, a small blood vessel surrounded by a clear Virchow-Robin space is seen.

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Designs of non-spiny stellate cells

Chandelier design Bouquet design

4. Glial cells: This is a group of supporting cells in the NS which are associating with the neurons.

- They include i. astrocytes ii. oligodendrocytes iii. ependymal cells iv. microgliae .

- They are occupying the neuropil part of the

cerebral cortex.

Cell cont………

Astrocytes

Normal astrocytes Cortical astrocytes – fluorecence technique

Ependymal cells

Study of neurons in the cerebral cortex involving staining techniques is known as artechitectonics.

- study by staining the cell bodies arrangements is termed cytoarchtechtonics.

- the use of myelin stained material is termed myeloarchtectonics.

- the use of stained pigment distribution is termed as pigmentoarchtectonics.

Study methodology

The pallium has six distinctive layers which may occasionally be appreciated by the naked eyes. The layers are lying parallel to the surface.

LAYER I: This is the molecular or plexiform layer.- it contains scattered horizontal cells and the apical dendrites of all pyramidal neurons of the cerebral cortex.

LAYER II: External granular lamina. - it contains small neuronal cell bodies (pyramidal and non pyramidal neurons).

LAYER III: External pyramidal lamina.- it contains pyramidal cells of different sizes.

LAYERS (LAMINAE)

LAYER IV: Internal granular layer.- this is the narrowest of the cellular laminae- it contains densely parked small round pyramidal cells

LAYER V: Internal pyramidal lamina.- it contains the larger pyramidal cells and scattered non-

pyramidal cells.

LAYER VI: The multiform layer.- it contains variety of shapes eg. Pyramidal, spindle, ovoid

and many other shaped somata. - the cells are small to medium sized.- this layer blends with the white matter.

Layers cont…..

Histological preparation of the Pallium (H & E)

Lamina of Pallium