Raman spectroscopy as an ex vivo noninvasive approach to distinguish complete and incomplete spermatogenesis within human seminiferous tubules

Objective To evaluate the potential clinical application of Raman spectroscopy (RS) as a tool that may identify spermatogenesis within human seminiferous tubules. Design RS scanning of human testicular tissue at different maturational stages; immunohistochemistry study and metabolomic analysis of nonobstructive azoospermic/obstructive azoospermic testes. Setting State-owned hospital. Patient(s) Fifty-two patients with clinical indications of nonobstructive azoospermia (NOA) and obstructive azoospermia (OA) who underwent infertility evaluation and treatment. Intervention(s) None. Main Outcome Measurement(s) Raman spectra of seminiferous tubules, thickness of lamina propria (LP), immunohistochemistry of type I, III, and IV collagens and laminin, metabolites of human testes. Result(s) Tubules of OA patients had spectral intensities below 2,000 (au), while tubules of NOA patients had higher intensities, depending on the degree of spermatogenesis. RS was able to separate samples of NOA and OA testicular tissue with a sensitivity of 90% and specificity of 85.71%. The LP of NOA tubules were thickened and had increased deposition of type I and type III collagens. Gas chromatography-mass spectrometer (GC-MS) detected 12 metabolites that showed significant differences between NOA and OA testes. Conclusion(s) RS can noninvasively distinguish seminiferous tubules with complete and incomplete spermatogenesis and may serve as a novel and potentially useful tool to guide surgeons performing micro-testicular sperm extraction to improve sperm retrieval.