Eye Histology Overview and Retina Structure

Study Notes

The eye has two main structural components: the pigmented (non-neural) epithelium and the neural retina.
The pigmented epithelium is a single layer.
The neural retina is made up of nine layers.

The retina is composed of two parts: pigmented and neural.
The pigmented epithelium is cuboidal cells specialized for vitamin A isomerization, absorbing scattered light, forming a blood-retina barrier, regenerating retinal, and removing free radicals.
The neural retina contains three major layers of nuclei: the outer nuclear, the inner nuclear, and the ganglion cells layers.
The outer nuclear layer includes the photoreceptor cells (rods and cones).
The inner nuclear layer includes bipolar cells, amacrine cells, and horizontal cells.
Ganglion cells have long axons that form the nerve fiber layer which leads to the optic nerve.

Rods are distributed all over the retina.
Rods are responsible for dim light vision.
Cones are concentrated in the fovea, responsible for high-intensity light vision and color.
Rods contain rhodopsin.
Cones contain iodopsin, three types related to color perception.
Rods are rod-shaped, while cones are conical.
Rods contain photoreceptor segments, cilia and mitochondria.
The metabolic region of both rods and cones include phospholipid and ATP production.

The retina has ten layers.
The layers include the pigmented layer, outer segment, outer limiting membrane, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, ganglion cell layer, nerve fiber layer, and inner limiting membrane.

The retina contains pigmented cuboidal cells, photoreceptor cells (rods and cones), bipolar cells, ganglion cells, and glial cells (Müller stem cells, amacrine cells, horizontal cells, and astrocytes).