TESMIN and Azoospermia: Male mice homozygous for the mutation showed spermatogenesis arrest at pachytene and azoospermia, exactly the same phenotype as in Mtl5 knockout (Mtl5-/-) mice, indicating that MTL5 is transported into the nuclei by LIN9 during zygotene-pachytene transition to promote meiotic progression beyond pachytene stage.