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Outer nuclear layer

Outer nuclear layer
Section of retina. (Outer nuclear layer labeled at right, fourth from the bottom.)
Plan of retinal neurons. (Outer nuclear layer labeled at left, third from the bottom.)
Gray's subject #225 1016
Dorlands/Elsevier l_05/12480791

The outer nuclear layer (or layer of outer granules or external nuclear layer), like the inner nuclear layer, contains several strata of oval nuclear bodies; they are of two kinds, viz.: rod and cone granules, so named on account of their being respectively connected with the rods and cones of the next layer.

Rod granules

The rod granules are much the more numerous, and are placed at different levels throughout the layer.

Their nuclei present a peculiar cross-striped appearance, and prolonged from either extremity of each cell is a fine process; the outer process is continuous with a single rod of the layer of rods and cones; the inner ends in the outer plexiform layer in an enlarged extremity, and is imbedded in the tuft into which the outer processes of the rod bipolar cells break up.

In its course it presents numerous varicosities.

Cone granules

The cone granules, fewer in number than the rod granules, are placed close to the membrana limitans externa, through which they are continuous with the cones of the layer of rods and cones.

They do not present any cross-striation, but contain a pyriform nucleus, which almost completely fills the cell.

From the inner extremity of the granule a thick process passes into the outer plexiform layer, and there expands into a pyramidal enlargement or foot plate, from which are given off numerous fine fibrils, that come in contact with the outer processes of the cone bipolars.

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 As such, some of the information contained herein may be outdated.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.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Outer_nuclear_layer". A list of authors is available in Wikipedia.
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