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Iris

posterior epithelium
striated muscles in the posterior part of the stroma
vascular network in the anterior part of the stroma
wavy appearance of the anterior part of the iris

Transverse section of the iris of a pigeon (HE)

The striated sphincter muscle and dilatator muscle are located in the posterior part of the stroma. Pigment cells and a vascular network are especially present in the anterior part. Bulging blood vessels give the anterior epithelium a wavy appearance.