Characterization of stage-specific tyrosinated α-tubulin immunoperoxidase staining patterns in Sertoli cells of rat seminiferous tubules by light microscopic image analysis

Microtubules are involved in many structural and functional changes that occur in Sertoli cells during the cycle of the seminiferous epithelium. However, few studies have addressed stage-specific changes in the distribution of microtubules that accompany the process of spermatogenesis. This study provides a stage-by-stage immunohistochemical evaluation of Sertoli cell microtubules in paraffin sections of whole rat testes using an antibody to tyrosinated α-tubulin. Microtubules that contain tyrosinated tubulin are considered to be less stable and are therefore expected to populate Sertoli cells undergoing dynamic changes during spermatogenesis. A quatitative method was developed to analyze the relative tyrosinated α-tubulin staining in different stages of the cycle. Immunostaining patterns of the stages were separated into five different groups. Stages VII-VIII had the least amount of tyrosinated α-tubulin, while stages IX-XI contained the greatest amount. The staining patterns were consistent with established structural changes in the seminiferous epithelium, such as the formation of ectoplasmic specializations, the presence of microtubule nucleation sites along the periphery of the apical cytoplasm, and the translocation of elongate spermatids from deep crypts in the Sertoli cell to the tubule lumen. These data should provide improved methods for the evaluation of microtubules in the study of Sertoli cell responses to environmental toxicants and testicular diseases.