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. 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.
Induced by: hybrid dysgenesis using the Birm2 chromosome.