Staging equine seminiferous tubules by Nomarski optics in unstained histologic sections and in tubules mounted in toto to reveal the spermatogenic wave.

Nomarski optics were used to identify stages of the spermatogenic cycle of seminiferous tubules in sectioned tissue or in whole dispersed tubules and to characterize the equine spermatogenic wave. Embedded tissues were sectioned at 20 microns. Whole dispersed tubules were obtained by enzymatic digestion of thin slices of fresh testis. Dispersed tubules were fixed, dehydrated in graded levels of alcohol, infiltrated with Epon, and mounted in toto on glass slides. Stages of the spermatogenic cycle could be identified under Nomarski optics in both histologic sections and tubules mounted in toto. Stage dependent nuclear chromatic and cytoplasmic changes in spermatogonia, spermatocytes, and spermatids were evident. Spermatid development included chromatin condensation, nuclear elongation, acrosomal development from the Golgi and proacrosomic granules, migration of the annulus and mitochondrial alignment, and the transient appearance of the chromatoid body and manchette. Both nuclear and cytoplasmic details of Sertoli cells were revealed. In tubules mounted in toto, the spermatogenic wave along the length of the tubules occurred as a consecutive set of stages occupying small regions along the tubular length. The spermatogenic wave in the horse is more similar to that of humans than that of rats. The combination of enzymatic isolation of seminiferous tubules and identification of spermatogenic stages by Nomarski optics facilitates examination of the spermatogenic wave in species whose tubules are tightly bound and not easily teased apart.