Figure 1.

Homologous chromosome association and dysjunction. (A) Schematic of male mouse spermatogenesis. Note the period of prophase during which HR promotes exchange of genetic information and homologous chromosomes pairwise interactions. (B) The presence of chiasmata ensures that each chromosome of the homologous chromosome pair segregates to opposite poles of the spindle. The homologous chromosome pairs are represented in red and yellow. Each of the homologous chromosomes comprises two sister chromatids represented by two bars of the same color. The green ovals represent cohesins.