Tetraploidy Determination in Rainbow Trout (Oncorhynchus mykiss) Based on Erythrocytes Dimensions

Tetraploidy induction at fish is characterized by modification of normal diploid chromosome set (2n) into tetraploid set (4n). Experiments were carried out on biological material from rainbow trout (Oncorhynchus mikiss) during the natural breeding season. Polyploidy was induced by exposing the eggs to heat shock. Blood smear was used as a technical method, to determine diploid and tetraploid status. Staining of blood smear was performed by Pappenhein method. The erythrocytes area and perimeter measurements done comparatively on tetraploid and diploid individuals may represent an indicator to determine the ploidy level of individuals. Erythrocytes area for tetraploid individuals is 2.18 times higher than at diploid individuals, and perimeter 1.45 times higher than in diploid individuals.