Substantia propria

From Wikipedia, the free encyclopedia

Substantia propria

Vertical section of human cornea from near the margin. (Waldeyer.) Magnified. 1. Epithelium. 2. Anterior elastic lamina. 3. substantia propria. 4. Posterior elastic lamina. 5. Endothelium of the anterior chamber. a. Oblique fibers in the anterior layer of the substantia propria. b. Lamellæ the fibers of which are cut across, producing a dotted appearance. c. Corneal corpuscles appearing fusiform in section. d. Lamellæ the fibers of which are cut longitudinally. e. Transition to the sclera, with more distinct fibrillation, and surmounted by a thicker epithelium. f. Small blood vessels cut across near the margin of the cornea.
Latin	s. propria corneae
Gray's	subject #225 1007
Dorlands/Elsevier	s_27/12766936

The substantia propria (or stroma of cornea) is fibrous, tough, unyielding, and perfectly transparent.

It is composed of about 200 flattened lamellæ, superimposed one on another.^[1] These fibrils run at different angles between limbi. Fibres of the layers frequently interweave, the anterior lamellæ interweaving more than posterior lamellæ. The fibres of each lamella are parallel with one another, but at right angles to those of adjacent lamellæ. The lamellæ are produced by keratocytes, which occupy about 10% of the substantia propria.

These lamellæ are made up of bundles of modified connective tissue, the fibres of which are directly continuous with those of the sclera. More collagen fibres run in a temporal-nasal direction than run in the superior-inferior direction. This is often ignored by corneal transplant surgeons, leading to poor corneal mechanical strength in corneal transplant patients.

Keratoconus is a condition caused by disorganised lamellæ, leading to a bulbous cornea.