Micrograph of a conjunctiva associated with prominent blood vessels (left-bottom of image) and elastotic collagen (centre of image), as may be seen in a<unk>  H&E stain.<unk> in the conjunctiva is characterized by elastotic degeneration of collagen (actinic elastosis) and fibrovascular proliferation. It has an advancing portion called the head of the<unk>  which is connected to the main body of the<unk> by the neck. Sometimes a line of iron deposition can be seen adjacent to the head of the<unk> called Stocker's line. The location of the line can give an indication of the pattern of growth. The predominance of pterygia on the nasal side is possibly a result of peripheral light focusing, where the sun's rays passing laterally through the cornea, where they undergo refraction and become focused on the limbic area. Sunlight passes unobstructed from the lateral side of the eye, focusing on the medial limbus after passing through the cornea. On the contralateral (medial) side, however, the shadow of the nose medially reduces the intensity of sunlight focused on the lateral/temporal limbus. Some research also suggests a genetic predisposition due to an expression of vimentin, which indicates cellular migration by the keratoblasts embryological development, which are the cells that give rise to the layers of the cornea. Supporting this fact is the congenital<unk>  in which<unk> is seen in infants. These cells also exhibit an increased P53 expression likely due to a deficit in the tumor suppressor gene. These indications give the impression of a migrating limbus because the cellular origin of the<unk> is actually initiated by the limbal epithelium. The<unk> is composed of several segments: * Fuchs' Patches (minute gray blemishes that disperse near the<unk> head) * Stocker's Line (a brownish line composed of iron deposits) * Hood (fibrous nonvascular portion of the<unk>  * Head (apex of the<unk>  typically raised and highly vascular) * Body (fleshy elevated portion congested with tortuous vessels) * Superior Edge (upper edge of the triangular or wing-shaped portion of the<unk>  * Inferior Edge (lower edge of the triangular or wing-shaped portion of the<unk> .
Pterygium 
Maxilla
Dipygus
Periorbita
Tophus
Ipas 
Nasolabial fold
Oral torus