Inner nuclear layer

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Inner nuclear layer
Section of retina. (Inner nuclear layer labeled at right, fifth from the top.)
Plan of retinal neurons. (Inner nuclear layer labeled at left, seventh from the top.)
Gray's subject #225 1016
Dorlands/Elsevier l_05/12480797

The inner nuclear layer or layer of inner granules is made up of a number of closely packed cells, of which there are three varieties, viz.: bipolar cells, horizontal cells, and amacrine cells.

Bipolar cells

The bipolar cells, by far the most numerous, are round or oval in shape, and each is prolonged into an inner and an outer process.

They are divisible into rod bipolars and cone bipolars.

  • The inner processes of the rod bipolars run through the inner plexiform layer and arborize around the bodies of the cells of the ganglionic layer; their outer processes end in the outer plexiform layer in tufts of fibrils around the button-like ends of the inner processes of the rod granules.
  • The inner processes of the cone bipolars ramify in the inner plexiform layer in contact with the dendrites of the ganglionic cells.

Horizontal cells

The horizontal cells lie in the outer part of the inner nuclear layer and possess somewhat flattened cell bodies.

Their dendrites divide into numerous branches in the outer plexiform layer, while their axons run horizontally for some distance and finally ramify in the same layer.

Amacrine cells

The amacrine cells are placed in the inner part of the inner nuclear layer, and are so named because they have not yet been shown to possess axis-cylinder processes.

Their dendrites undergo extensive ramification in the inner plexiform layer.

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This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.