Sequential Development of Albino Rabbit Iris During Fetal and Postnatal Life: Histological, Ultrastructural, and Immunohistochemical Investigations

The iris has several unique structures that are determined by its embryonic origin. Therefore, this research aimed to demonstrate the morphogenesis of the albino rabbit iris. The development of the rabbit iris began at mid-gestation and was completed postnatally. Consequently, we used 36 embryos and 12 neonatal rabbits. The iris originated from the tip of the optic cup. The epithelium of the iris began to differentiate on day 15 of pregnancy, forming a single layer of epithelial cells. The constrictor muscle began its differentiation on day 27 of pregnancy in the area around the pupil, while the dilator muscle differentiated on day 30 as a protrusion from the anterior epithelial cells. The stroma of the iris differentiated from the periocular mesenchyme into fibroblasts, telocytes, dendritic cells, and macrophages. The tyrosinase enzymes expressed in the albino rabbit's iris were inactive and at low levels, with melanocytes lacking melanin pigment. Vimentin immunohistochemistry expression was observed in all layers of the iris. Desmin was expressed only in the constrictor muscle and stroma. Explaining the developmental process of the albino's iris is vital for advancing our knowledge of this tissue.