Pigmentary Layer
The Pigmentary Layer (also known as the "Tapetum Nigrum") is the tenth (10th) of the layers forming the retina of the human eye.
Recall that light from outside the human body enters the eye through its main structures of the cornea, aqueous humour, pupil, lens, etc. and is normally focussed onto the retina of the eye.
The retina is composed of several layers which, together, form the "screen" in the eye onto which an image of the area viewed by the eye is formed, and information about that image is segmented into packets of information that are passed to the visual cortex of the brain via the optic nerve.
The pigmentary layer (or "Tapetum
Nigrum") is
the most external - i.e. the most distant from the centre of the
eye, layer of the retina. It consists of a single layer of hexagonal
epithelial cells that contain pigment granules. The posterior (external)
surface of these epithelial cells is smooth, and in contact with
the choroid
layer. The internal surfaces of these pigmented cells takes the form of straight
processes extending inwards between the rods - as shown in the pigment
layer at the top right-hand side of the top-right image on
this page.
Note that the pigmentary cells are also present in albinos, the key difference being that in their cases the pigment granules are not present.
For more information about related subjects see:
- Structure of the human eye
- Structure of the human retina
- What is ophthalmology?
- List of disorders of the human eye
- List of ophthalmic procedures
- Textbooks about ophthalmology
