Lens and Zonules Flashcards
Lens is mainly made up of what kind of tissue? What happens to the center cells with age?
Epithelium
They become anucleate therefore cannot regenerate may be one of causes of cataract.
Is the lens vascular? Does it grow with age? what are the cells called in the lens?
NO, YES, fibres
What are the three parts of the lens?
- Lens capsule (thinnest at poles, thicker in center)
- Lens epithelium (cuboid on anterior surface, columnar cells by equator)
- Lens fibres (hexagonal, lose nuclei as we age)
Lens capsule has what kind of fibres? insertion site of what? which is thicker anterior or posterior capsule? older material of lens is located where?
collagen
zonules
Anterior (thickens with age)
center of lens
Does epithelium line the back of the lens?
NO. just front.
what us lens bow?
where nuclei move anteriorly to get deeper into lens.
Embryonic nucleus of lens is formed by? Secondary lens fibres form what nucleus?
primary lens fibres (highest n) Fetal nucleus (laid down before birth), Adult nucleus (birth to sexual maturation) and cortex (after sexual maturity, lowest n)
Anterior suture of lens overlaps what? posterior suture? During development these sutures form what shape? Once we get to adult nucleus are the sutures this simple?
apical aspects, basal aspects.
Y
no, they are more complex than y structure.
Zonules also called? they attach how far from anterior of equator?, how far from posterior of equator? what makes up the zonule itself?
suspensory ligaments
Ant: 2mm, Post: 1mm
fibrils->fibres->bundles
choroid is located between what two layers?
sclera and retina
Function of canal of cloquet? lined with what kind of fibres?
nourishes developing lens, gradually retracts.
collagen
Aging of lens can occur due to?
UV irridation: absorbs all UV, causes epithelium damage lens fibres degrade and modifies lens crystallins.
Lens grows throughout life: increases curvature, presbyopia, inability to accommodate.
Cataract due to?
Necrosis of secondary fibres.
