The separation, physical characterization, and differentiation kinetics of spermatogonial cells of the mouse.

By means of the velocity sedimentation technique for cell separation, single cell suspensions from the testes of the mouse could be separated into at least seven peaks each with a different sedimentation velocity. These were named and characterized as follows: alpha (12 mm/hr); beta (10 mm/hr); gamma (6.5 mm/hr); delta (4.3 mm/hr); theta (broad peak with median 2.5 mm/hr); kappa (1.1 mm/hr); lambda (0.75 mm/hr). Tritiated thymidine was injected into thirty groups of mice. The spermatogonial cells of each group were separated at one hour and then at daily intervals, and the acid insoluble activity of each fraction was measured. This method enabled us to determine the differentiation patterns of mouse spermatogenesis by following the thymidine label with time. It was found that the spermatogonia and primary spermatocytes formed the theta peak with S-phase spermatogonia and primary spermatocytes having a similar sedimentation velocity of 2.1 mm/hr. The beta cells were identified as late pachytenes and diplotene cells, the gamma cells as secondary spermatocytes, the delta cells as earliest spermatids, the kappa cells as spermatids, and the lambda cells as mature spermatozoa.