Stroma of cornea

Stroma of cornea
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.
Details
Identifiers
Latin	substantia propria sclerae
Dorlands /Elsevier	s_27/12766936
TA	A15.2.02.009
FMA	58365
Anatomical terminology [edit on Wikidata]

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

It is composed of about 200 flattened lamellæ (plates of collagen fibrils), superimposed one on another.^[1] They are each about 1.5-2.5 micrometres in thickness. These fibrils run at different angles between the 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 (corneal corpuscles), 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.

During development of the embryo, the corneal stroma is derived from the neural crest (a source of mesenchyme in the head and neck^[2]) which has been shown to contain mesenchymal stem cells.^[3]

Disorders of stroma

• Keratoconus is a condition caused by disorganised lamellæ, leading to thinned and conical-shaped cornea.
• Macular corneal dystrophy, associated with the loss of keratan sulfate

References

1. ↑ Oyster, CW (1999). "8". The human eye: structure and function. Sinauer. OL 8562710W. 
2. ↑ Hoar RM (Apr 1982). "Embryology of the eye". Environ Health Perspect. 44: 31–34. doi:10.1289/ehp.824431. PMC 1568953. PMID 7084153. 
3. ↑ Branch MJ, Hashmani K, Dhillon P, Jones DR, Dua HS, Hopkinson A (Aug 3, 2012). "Mesenchymal stem cells in the human corneal limbal stroma". Invest Ophthalmol Vis Sci. 53 (9): 5109–16. doi:10.1167/iovs.11-8673. PMID 22736610. 

External links

• Diagram at pacificu.edu

Anatomy of the globe of the eye Fibrous tunic (outer) Sclera Episcleral layer Schlemm's canal Trabecular meshwork Cornea Limbus layers Epithelium Bowman's Stroma Descemet's Endothelium Uvea/vascular tunic (middle) Choroid Capillary lamina of choroid Bruch's membrane Sattler's layer Ciliary body Ciliary processes Ciliary muscle Iris Stroma Pupil Iris dilator muscle Iris sphincter muscle Retina (inner) Layers Inner limiting membrane Nerve fiber layer Ganglion cell layer Inner plexiform layer Inner nuclear layer Outer plexiform layer Outer nuclear layer External limiting membrane Layer of rods and cones Retinal pigment epithelium Cells Photoreceptor cells (Cone cell, Rod cell) → (Horizontal cell) → Bipolar cell → (Amacrine cell) → Retina ganglion cell (Midget cell, Parasol cell, Bistratified cell, Giant retina ganglion cells, Photosensitive ganglion cell) → Diencephalon: P cell, M cell, K cell, Muller glia Other Macula Foveola Fovea centralis Parafovea Perifovea Optic disc Optic cup Anterior segment Anterior chamber Aqueous humour Posterior chamber Lens Capsule of lens Zonule of Zinn Posterior segment Vitreous humour Other Asthenopia Keratocytes Ocular immune system Tapetum lucidum