In this study, we invesgated a cytogenetic analysis of the Pacific triploid abalone, Haliotis discus hannai induced by low temperature treatment. We got a lot of mitotic metaphase chromosome spreads from the triploid and diploid Pacific abalones' hatched larvae (trochophores). The chromosome number of diploid abalone was 2n = 36 and that of triploid abalone was 3n = 54, so the chromosome number of triploid abalone was 1.5 times higher than that of diploid abalone. We developed a modified flow

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... tometric method for Pacific abalone from the existing methods. We uesd 51 months aged triploid and diploid Pacific abalones' hemolymph to get the DNA contents by flow cytometry. The DNA content of diploid abalone was 1.743 pg/cell and the DNA content of triploid abalone was 1.49 times higher than that of diploid one. It proved that triploid abalone was consisted with two sets of maternal diploid and one set of paternal genome.