"crossing over of chromosomes" . . "crossover" . "crossing-over" . "crossover recombinants" . "recombined" . . . . "homologous recombination" . "crossed over" . "crossovers" . "Crossovers" . . . "exchange of genes (crossing over and recombination)" . "meiotic crossing over" . . . "Chromosomal crossover" . "chromosomal crossover" . "crossing over" . "exchange of genetic material" . "crossing" . "genetic crossover" . "inter-homolog exchange" . "Chromosomal crossover" . "DNA crossover" . "recombination" . . "genetic exchange" . "crossover recombination" . "Crossing over" . "Crossover" .