Hakimeh Abdali - Fisheries Department, University College of Agriculture and Natural Resources, faculty of Natural resources, University of Tehran, Iran
Soheil Eagderi - Fisheries Department, University College of Agriculture and Natural Resources, faculty of Natural resources, University of Tehran, Iran
Pagah Zargarian - Science and Research Branch, Islamic Azad University, Tehran, Iran

This research was conducted to study the ontogeny of visual structure and retina ofSterlet (Acipenser ruthenus) during early development from hatching up to 50 DPH(day post hatching). For this purpose histological sections of eye during this periodwere prepared using paraffin method and stained by hematoxilin-eosin. At hatchingtime, the retina was not differentiated and differentiation of eye layers were startsfrom 2 DPH. Main developmental changes in Sterlet eye were occurred at 3 DPH. Atthis time, eye wall, lens, iris, choroid layer, scleral layer, cornea and vitreous humourwere observable. In addition, differentiation of the retina with a high intensity of conevisual cells was observed at 3 DPH. The retina was developed as several layers withincreasing intensity of rod visual cells at 9 DPH. Upon 25 DPH, most of visualstructures and retina were fully developed and eye structure was similar to those ofadult fish. The results revealed that ontogeny of visual structures and cells is occurredin accordance with changes in biological demands and habitat changes i.e. beginningof exogenous feeding and benthic life style of Sterlet.

Starlet, Ontogeny, Eye structure, Histology