Stroma of iris
The stroma
Stroma (animal tissue)
In animal tissue, stroma refers to the connective, supportive framework of a biological cell, tissue, or organ.The stroma in animal tissue is contrasted with the parenchyma.Examples include:* Stroma of iris...

 of the iris
consists of fibers and cells.

The former are made up of delicate bundles of fibrous tissue; a few fibers at the circumference of the iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...

 have a circular direction; but the majority radiate toward the pupil
The pupil is a hole located in the center of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. In humans the pupil is round, but other species, such as some cats, have slit pupils. In...

, forming by their interlacement delicate meshes in which the vessels and nerves are contained.

Interspersed between the bundles of connective tissue are numerous branched cells with fine processes.

In dark eyes many of them contain pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...

 granules, but in blue eyes and the eyes of albinos they are unpigmented.
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