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The stroma around the iris sphincter muscle becomes darker than the peripheral stroma. [medical citation needed] A stimulation of melanin synthesis within iris melanocytes has been postulated. [21] Neoplasm – Nevi and melanomatous tumors. Iridocorneal endothelium syndrome [3] Iris ectropion syndrome [3] [22]
Choroidal nevus (plural: nevi) is a type of eye neoplasm that is classified under choroidal tumors as a type of benign (non-cancerous) melanocytic tumor. [1] A choroidal nevus can be described as an unambiguous pigmented blue or green-gray choroidal lesion, found at the front of the eye, around the iris, [2] or the rear end of the eye.
Melanin is the primary determinant of the degree of skin pigmentation and protects the body from harmful ultraviolet radiation. The same ultraviolet radiation is essential for the synthesis of vitamin D in skin, so lighter colored skin – less melanin – is an adaptation related to the prehistoric movement of humans away from equatorial ...
In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. [4]
Albinism results in the reduction of melanin production only, though the melanocyte (or melanophore) is still present. Thus in species that have other pigment cell-types, for example xanthophores, albinos are not entirely white, but instead display a pale yellow color.
BCEM, also referred to as conjunctival hypermelanosis, complexion-associated melanosis, or racial melanosis, is a non-cancerous lesion of the conjunctiva that is more commonly found in dark-skinned individuals (over 90% of lesions are found in black persons and around 5% in white persons). [1]
Melanin is yellowish to dark hazel in the stromal pigment cells, and black in the iris pigment epithelium, which lies in a thin but very opaque layer across the back of the iris. Most human irises also show a condensation of the brownish stromal melanin in the thin anterior border layer, which by its position has an overt influence on the ...
Iris suaveolens is a plant species in the genus Iris, it is also in the subgenus Iris. It is a rhizomatous perennial, from Eastern Europe, ranging from the Balkans to Turkey (in Asia Minor). It has short, sickle shaped or curved, blue-green or greyish green leaves, a slender simple stem, with 1 or 2 fragrant spring blooming, flowers, between ...