Nondisjunction, GeneticMeiosisChromosomes, Human, Pair 21AneuploidyCrossing Over, GeneticDown SyndromeTrisomySex ChromosomesAbnormalities, Radiation-InducedChromosomesChromosome SegregationX ChromosomeMaternal AgeChromosome AberrationsRecombination, GeneticY ChromosomeCrosses, GeneticPotoroidaeCentromereChromosomes, FungalMitosisChromatidsTranslocation, GeneticSecale cerealeChromosome MappingChromosomes, InsectMosaicismDiploidyGenetic TechniquesPaternal AgeGenetic MarkersNucleolus Organizer RegionChromosome DisordersKaryotypingIn Situ Hybridization, Fluorescencep-FluorophenylalanineDrosophila melanogasterSex Chromosome AberrationsX-RaysChromosomes, Human, Pair 18SpermatocytesMetaphaseMutagensChromosomes, Human, Pair 13OocytesHygromycin BPhosphoribosylglycinamide FormyltransferaseMutationSister Chromatid ExchangeHeterozygoteSynaptonemal ComplexChromosome BreakagePolyploidyMonosomyChromosome BandingChromosomes, PlantPollenSporesSpermatozoaAnaphaseZea maysDrosophilaSaccharomyces cerevisiae