Clearing, immunofluorescence, and confocal microscopy for the three-dimensional imaging of murine testes and study of testis biology.

Optical clearing techniques provide unprecedented opportunities to study large tissue samples at histological resolution, eliminating the need for physical sectioning while preserving the three-dimensional structure of intact biological systems. There is significant potential for applying optical clearing to reproductive tissues. In testicular biology, for example, the study of spermatogenesis and the use of spermatogonial stem cells offer high-impact applications in fertility medicine and reproductive biotechnology. The objective of our study is to apply optical clearing, immunofluorescence, and confocal microscopy to testicular tissue in order to reconstruct its three-dimensional microstructure in intact samples. We used Triton-X/DMSO clearing in combination with refractive index matching to achieve optical transparency of fixed mouse testes. An antibody against smooth muscle actin was used to label peritubular myoid cells of seminiferous tubules while an antibody against ubiquitin C-terminal hydrolase was used to label Sertoli cells and spermatogonia in the seminiferous epithelium. Specimens were then imaged using confocal fluorescence microscopy. We were able to successfully clear testicular tissue and utilize immunofluorescent probes. Additionally, we successfully visualized the histological compartments of testicular tissue in three-dimensional reconstructions. Optical clearing combined with immunofluorescence and confocal imaging offers a powerful new method to analyze the cytoarchitecture of testicular tissue at histological resolution while maintaining the macro-scale perspective of the intact system. Considering the importance of the murine model, our developed method represents a significant contribution to the field of male reproductive biology, enabling the study of testicular function.