Nondisjunction, GeneticMeiosisChromosomes, Human, Pair 21AneuploidyCrossing Over, GeneticDown SyndromeTrisomySex ChromosomesAbnormalities, Radiation-InducedChromosomesChromosome SegregationX ChromosomeRecombination, GeneticChromosome AberrationsMaternal AgeY ChromosomeCrosses, GeneticCentromerePotoroidaeChromosomes, FungalMitosisChromatidsTranslocation, GeneticChromosome MappingSecale cerealeMosaicismDiploidyChromosomes, InsectGenetic MarkersGenetic TechniquesPaternal AgeNucleolus Organizer RegionChromosome DisordersKaryotypingIn Situ Hybridization, Fluorescencep-FluorophenylalanineDrosophila melanogasterSex Chromosome AberrationsX-RaysMutationChromosomes, Human, Pair 18SpermatocytesMutagensMetaphaseOocytesChromosomes, Human, Pair 13Hygromycin BPhosphoribosylglycinamide FormyltransferaseHeterozygoteSister Chromatid ExchangeSynaptonemal ComplexChromosome BreakagePolyploidyChromosome BandingMonosomyChromosomes, PlantPollenSpermatozoaSporesDrosophilaAnaphaseZea maysSaccharomyces cerevisiaeAllelesGenes, DominantGenotype