The influence of triploidization on cell and nucleus size characteristics of the same tissues of erythrocyte,
retina, kidney, hepatocyte and midgut epithelium in marine medaka, Oryzias dancena has been determined histologically.
Induced triploid fish are produced by cold shock treatments. Likewise, the size of horizontal cell nucleus in inner nuclear layer
of retina, ganglion cell nucleus in ganglion cell layer of retina, proximal tubule cell of kidney, hepatocytes and nuclear height
of midgut epithelium all appear to be significantly larger than diploid (P<0.05). On the other hand, retina thickness is larger in diploid than induced triploid (P<0.05). Induced triploid shows low density of cell number. Results of this study suggest that same characteristics in the induced triploid exhibiting larger cells and nucleus sizes with fewer number of cells than the diploid can be useful criteria for the distinction between diploid and induced triploid, and also the ploidy level in marine medaka.

• In Bon Goo(Inland Aquaculture Research Center, National Fisheries Research & Development Institute) Corresponding author
• Jae Hyun Im(Inland Aquaculture Research Center, National Fisheries Research & Development Institute)
• Hyun Woo Gil(Dept. of Marine Bioscience, College of Ocean Science and Technology, Korea Maritime and Ocean University)
• Sang Gu Lim(Future Aquaculture Research Center, National Fisheries Research & Development Institute)
• In-Seok Park(Dept. of Marine Bioscience, College of Ocean Science and Technology, Korea Maritime and Ocean University) Co-corresponding author