VPB 121: Veterinary Physiology - II (2+1)

CYTO ARCHITECTURE OF CEREBRAL CORTEX

• Six functionally distinct layers have specific pattern of neuronal cell bodies.
• Variation exits between shape and density of neurons located in each layer.
  • Molecular layer:  Most superficial layer has many dendritic, axons and glial cells from a felted mat like appearance. Few cell bodies and few connections among cells.
  • External granular layer:  Has many different shaped [angular, polygonal, triangular, round cells] whose axon end in deep layers. Cells are many, fibers are less and integrates signals within in the cortex.
  • External pyramidal layer:  Has pyramidal cells whose size increase gradually.
  • Internal pyramidal layer or ganglion layer:  Has graded sizes of pyramidalcells-giant pyramidal cells viz. BETZ cells are seen .This type of cellular architecture is evident is precentral cortex. Communication with other parts like thalamus, brain stem and spinal cord.
  • Internal granular layer:  Has number of small stellate cells.it has rich nerve fibres, horizontal crisscrossing fibres pose a white band like appearance.
  • Fusiform cells layer:  Has small spindle shaped cells that are matted perpendicular to the surface.