Errors in chromosome partitioning during meiosis result in aneuploid gametes that form embryos that die, arrest in development or have developmental abnormalities. Most of meiosis is devoted to temporarily connecting each maternally-derived homologous chromosome to its paternally-derived counterpart. These connections are generated by crossover recombination and are key in enabling the ordered partitioning the genome in the two meiotic divisions. In the first division, the connected homologous chromosomes are partitioned while keeping sister chromatids together in each homolog until the second nuclear division. The REC-8 cohesin is required for sister chromatids to segregate together to the same spindle pole in this division. Mutants that fail to form crossovers result in separate maternally- and paternally-derived homologous chromosomes. Observations by Severson et al. (2009) suggest that meiotic mutants that do not undergo crossover recombination segregate the homologous chromosomes in one of two ways in the first meiotic division of oocytes. In meiotic mutants that have REC-8, sister chromatids co-orient and each homologous chromosome segregates randomly. In meiotic mutants that lack REC-8, sister chromatids bi-orient and segregate away from each other in the first meiotic division. We will report our observations of chromosome partitioning defects in spermatocytes of meiotic mutants. Unlike mutants lacking REC-8, meiotic mutants defective in different steps leading to crossover recombination including; him-3, syp-1, syp-2 and spo-11, fail to partition their chromosomes in the first division. These mutants still progress into the second meiotic division and form multipolar or connected spindles with bi-oriented sister chromatids that segregate to form four mostly aneuploid spermatids. Interestingly, analysis of spo-11 mutant spermatocytes suggests that a single bi-oriented homologous chromosome pair is sufficient to suppress the formation of abnormal spindle organization in these mutants. The SPO-11 protein makes the double strand DNA breaks required for the initiation of crossover recombination. spo-11 mutants can be rescued by inducing exogenously the formation of double strand DNA breaks. Induction of a single double strand break per nucleus generates one homologous chromosome pair. The formation of a single homologous chromosomes pair is sufficient to suppress the abnormal spindle organization seen in these mutant spermatocytes. We are currently investigating the cellular mechanism by which a single homologous chromosome pair might promote normal bi-polar spindle organization and segregation of meiotic mutant chromosomes that otherwise would not be partitioned in the first division.