Homozygous lethal but viable and female fertile over can1, can2 or can3. Early stages of spermatogenesis up through mature primary spermatocytes are present and normal. Postmeiotic stages are completely absent. Mutant testes have an abundance of mature primary spermatocytes with large, round nuclei and prominent nucleoli. Spermatocytes arrest in the G2/M transition of meiosis I with partial chromosome condensation.