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The stroma is a delicate interlacement of fibres. Some circle the circumference of the iris and the majority radiate toward the pupil. Blood vessels and nerves intersperse this mesh. In dark eyes, the stroma often contains pigment granules. Blue eyes and the eyes of albinos, however, lack pigment.
The iris consists of two layers: the front pigmented fibrovascular layer known as a stroma and, behind the stroma, pigmented epithelial cells.. The stroma is connected to a sphincter muscle (sphincter pupillae), which contracts the pupil in a circular motion, and a set of dilator muscles (dilator pupillae), which pull the iris radially to enlarge the pupil, pulling it in folds.
The cells which make up stroma tissues serve as a matrix in which the other cells are embedded. [2] Stroma is made of various types of stromal cells. Examples of stroma include: stroma of iris; stroma of cornea; stroma of ovary; stroma of thyroid gland; stroma of thymus; stroma of bone marrow; lymph node stromal cell; multipotent stromal cell ...
The anterior segment or anterior cavity [1] is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens. [2] [3] Within the anterior segment are two fluid-filled spaces: the anterior chamber between the posterior surface of the cornea (i.e. the corneal endothelium) and the ...
An area termed the limbus connects the cornea and sclera. The iris is the pigmented circular structure concentrically surrounding the centre of the eye, the pupil, which appears to be black. The size of the pupil, which controls the amount of light entering the eye, is adjusted by the iris' dilator and sphincter muscles.
The irises of human eyes exhibit a wide spectrum of colours. Eye color is a polygenic phenotypic trait determined by two factors: the pigmentation of the eye's iris [1] [2] and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris.
The uvea (/ ˈ j uː v i ə /; [1] derived from Latin: uva meaning "grape"), also called the uveal layer, uveal coat, uveal tract, vascular tunic or vascular layer, is the pigmented middle layer of the three concentric layers that make up an eye, precisely between the inner retina and the outer fibrous layer composed of the sclera and cornea.
The corneal limbus manifests as a dark ring around the iris. Its prominence varies by individual. The corneal limbus is the border between the cornea and the sclera. [1] It is highly vascularised. [1] Its stratified squamous epithelium is continuous with the epithelium covering the cornea. [2]