Evaluation of Stallion Testicular Cell Types by Flow Cytometry

Flow cytometry procedures can be used for evaluation of both spermatogenic efficiency and diagnose disorders of stallion spermatogenesis. Aims of this study were to compare two testicular sample acquisition techniques (needle aspirate-N and tissue wedge-T) and results when using flow cytometry and histology procedures. Testicular cell types were stained with acridine orange, and nine regions (R2 to R10) were identified and enumerated following acquisition by either N or T. Testes were also grouped and analyzed by size and sexual maturity (Small [immature] compared with Large [mature]) and used to determine if flow cytometry procedures could be used to detect differences. For both N and T, percentages of 2n cell types were greater in the Small than Large testes, whereas percentages of 1n cell types in N were greater in the Large than Small testes (P < .05). Testicular cell types in N regions were correlated to similar T regions (r between 0.51 and 0.99; P < .05) in both groups. Flow cytometry and histology scores were correlated in both groups (r between -0.95 and 0.93, P < .05). There were small differences in number of testicular cell types from N and T. With both sample acquisition methods, there was discrimination between the Small and Large testes, therefore, evaluation of testicular cell types using flow cytometry procedures might have clinical applications. Results with comparison of flow cytometry to histology procedures indicate that flow cytometry can be applied clinically to identify changes in testicular cell types of stallions using a needle aspirate.