Science Is Fun By Tomas Rosko on Instagram: "What you see: The iris is made up of several layers. The visible texture is largely the arrangement of the anterior border layer and the underlying stroma, which consists of connective tissue (trabeculae) and blood vessels. The fibers you see running from the edge toward the center (the edge of the pupil) represent the radial pattern created by the arrangement of the iris muscles and blood vessels. These are sometimes referred to as: • Radial Contract