Apoptosis in male germ cells in response to cyclin A1-deficiency and cell cycle arrest
Male mice homozygous for a mutated allele of the cyclin A 1 gene (Ccna 1) are sterile due to a block in cell cycle progression before the first meiotic division. Meiosis arrest in Ccna1(-1-) spermatocytes is associated with desynapsis abnormalities, lowered MPF activity, and apoptosis as evidenced by TUNEL-positive staining. With time, adult testicular tubules exhibit severe degeneration: some tub