Observations on living rat spermatogenic cells in different developmental stages.

In the seminiferous tubules of the rat, as in most mammalian species, the developing germ cells form associations with constant cell composition. These cellular associations or stages follow each other in a regular manner along the seminiferous tubules giving rise to seminiferous epithelial wave. When a freshly isolated unstained seminiferous tubulus of the rat is subjected to transillumination under a stereomicroscope, the different segments of the seminiferous epithelial wave absorb light in a characteristic manner permitting their recognition. Using this technique, small segments with accurately known cell composition can be isolated and studied in living state with phase-contrast microscopy. In several cases, the phase-contrast microscopy gives more information about the cell morphology than conventional histological methods. In this study all major developmental steps from early spermatogonia to mature spermatids have been described. The findings of the present study can be used as reference material in the evaluation and identification of the various cell types of the seminiferous tubules obtained, e.g. by the Staput fractionation method. In addition, the findings may be helpful in the evaluation of spermatogenic and Sertoli cells in culture conditions.