Histology Flashcards
Latin terminology for the eye?
Bulbus oculi
Components of the bulbus oculi?
Three layers - outer supporting - middle - inner Accessory structures
Components of the outer supporting layer of the eye?
Cornea
Corneoscleral junction (limbus)
Sclera
What does the cornea consist of, histologically?
Transparent and avascular anterior supporting layer with nutrition from endothelium
- Outer layer (squamous stratified epithelium)
- Bowman’s membrane (acellular, collagen)
- Substantia propria (thickest layer, 25 pallel lamellae of collagen fibres)
- Descemet’s membrane (basement membrane)
- Inner layer (Descemet’s endothelium)
Another term for the substance propria of the cornea?
Stroma
Histology of the limbus
+/- 1mm transition zone from corneal epithelium to scleral epithelium
Functions of the sclera
Protect the eye
Maintain intraocular pressure
Insertion point of extrinsic ocular muscles
What does the sclera consist of, histologically?
Dense connective tissue (mostly collagen (fibroblasts) + some elastic fibres)
Few blood vessels
No lymphatics
Components of the middle layer of the eye?
Choroid
Ciliary body
Iris
What does the choroid consist of, histologically?
- Suprachoroid (collagen, elastic fibres + melanocytes)
- Vessel layer (thickest, many blood vessels with loose CT + melanocytes)
- Choriocapillary (single capillaries, wide lumens, fenestrated endothelium)
- Bruch’s membrane
What does Bruch’s membrane of the choroid consist of, histologically?
- Outer basal membrane of choriocapillary
- Collagen fibres
- Network of elastic fibres
- Collagen fibres
- Inner basal lamina of the pigment epithelium
What is the structure of the ciliary body, histologically?
Loose connective tissue rich in elastic fibres, vessels + melanocytes
Surrounded by ciliary muscle
Simple columnar cells rich in melanin
Derived from sensory layer of the retina (simple, non-pigmented columnar epithelium)
What is the structure of ciliary muscle, histologically?
2 bundles of smooth muscle
What is the structure of the ciliary processes, histologically?
Ridge-like extensions of he ciliary body
Loose CT core
Numerous fenestrated capillaries covered by the same epithelium
Zonule fibres from the ciliary processes insert in the lens capsule
What are fenestrated capillaries?
Capillaries with pores that allow larger molecules through for extensive molecular exchange with the blood
What is the structure of the iris, histologically?
Circular diaphragm with a distensible aperture (pupil)
An extension of the choroid that partially covers the lens
Has a rough, irregular anterior surface with grooves and ridges
What does the iris consist of, histologically?
- Endothelium
- Stromal layer
- Vessel layer
- Smooth muscle layer
- Pigmented epithelium layer
What is the structure of the zonula, histologically?
Suspensory ligaments of the lens that consist of filaments and bundles of fibres
Attached to ciliary body and lens equator