The survey of cellular sequence of the retina structure of the Beluga Sturgeon eye (Huso huso)

˜یÏå [English]
Huso huso is one of the most important commercially valuble sturgeons of Caspian Sea. Vision is an important sense particulaurly for fishes like H. huso. It is assumed that H. huso as a benthic fihsh may have weak color vishion and accurecy and therefor retina structure was studied. Such study not only show importance of vision to fish species but also obtained information bring about considerable relationship between feeding, envirenment and animal behaviour with vision. Eyes wen dissected out and cornea and lens were remoted.
Retina alone was first fixed in Bouins solution for 24 hours and secondly in 70% methanol for another 24 hours. Tissue has dehydrated, cleared and made in to blocks of paraffin. 5µ thick sections is transverse and sagittal planes were taken and stained by hematoexyline and eosin.
Some section of the best tissue band selected and transfered to 45º C water. Then it was cleared and dehydrated and photography with electron microscope. Histological and SEM observations showed that H. huso retinal photoreceptors was comprised of both rod and cone cells. Single, twin and double cones were found.
Presence of different types of cones render the colour vision in H. huso. The number of cone cells in dorso – temporal quadrant was more compared to others. So dorso – temporal region with higher cone density play a role in benthic feeding of fish. Also H. huso possess weak visual sense.