Testicular DNA synthesis in vivo: comparison between unilaterally cryptorchid testis and contralateral intact testis in mouse.

DNA synthetic activity was studied by autoradiography in unilaterally cryptorchid (abdominal) and contralateral intact(scrotal) testes in mice. Nongerm cells were inactive in DNA synthesis in both the cryptorchid testis and in the intact control. Labeling indices of undifferentiated type A spermatogonia did not show any differences, indicating that type A spermatogonia did not temperature sensitive in DNA synthesis in vivo.