简介：ArtificiallyinducedtetraploidPacificoyster,CrassostreagigasThunberg,producesmoreaneuploidgametesthannormaldiploidone,althoughtheyshowedacomparablefecunditytodiploidy.Themeioticchromosomeconfigurationof3tetraploidand1tetraploid/triploidmosaicmaleswereanalyzedthroughdirectchromosomeobservation.AmajorityofmetaphaseIspermatocytescontainedbothbivalentsandquadrivalents.Thechromosomeconfigurationofthesemaleswascharacterizedbypreferentialformationofbivalentstoquadrivalents.Bivalentsappearedinallspermatocytesandconsistedof86%ofallchromosomeaggregates.Incomparison,quadrivalentsoccurredin91%spermatocytesandconsistedofonly12.6%ofallchromosomeaggregates.Themeanbivalentfrequencyperspermatocytevariedbetween14.4and17.2;whilethatofquadrivalentsvariedbetween2.2and2.7.Mostquadrivalentsweretandemlychained(58%)orcircled(39%).Thetotalnumberofchromosomeaggregatesperspermatocyterangedfrom13to20withanaverageof17.6;while18(16bivalentsand2quadrivalents)wasthemostfrequent.Univalentsandtrivalentsappearedinverylowfrequency.Aneuploid(hypotetraploid)spermatocyteswereobservedinalowfrequency.Thechromosomeconfigurationofinthemosaicindividualwassimilartothatoftetraploidindividuals.Thepercentageoftriploidspermatocytes(2%)ofthemosaicindividualwassignificantlylower(χ2=30,P<0.01)thanthatoftriploidcells(46%)initssomatictissue.