Vimentin expression in testes of Arabian stallions

Specific patterns of cytoskeletal filaments reflect a functional state of the cell. In testicular cells intermediate filaments (IFs) are of the vimentin type. Since it is known that Sertoli cells regulate the spermatogenic function in the male gonad, it became important to propose a system that could quantify the state of seminiferous tubular quality. To date, a Johnsen score system has never been used to equine testes.

To demonstrate the expression pattern of vimentin in testes of mature Arabian stallions and correlate its distribution with grade of seminiferous tubule impairment as indicated by a Johnsen score.

For histological examination by the Johnsen method, routine haematoxylin-eosin staining was used. Vimentin expression and its presence in testicular sections and testicular homogenates were detected by immunohistochemistry and western blot, respectively. Both analyses were performed qualitatively and quantitatively and further validated by ANOVA tests.

Distinct morphology of seminiferous tubules was found in testes harvested from 3 stallions. Vimentin in IFs was immunolocalised to the cytoplasm of Sertoli, Leydig and peritubular-myoid cells. The intensity and pattern of the IFs staining was different in individual seminiferous tubules suggesting a correlation between vimentin expression and the severity of tubule degeneration. Qualitative results by immunohistochemistry and western blot were confirmed by further quantitative analyses.

In equine testes, differential expression of vimentin was found to be correlated with the impairment of seminiferous tubules indicated by a decrease in Johnsen score.

The Johnsen score system may be a useful method to facilitate the identification of tubular alterations in the stallion testes. Combined histological and immunohistochemical approach may provide a detailed phenotypic classification of stallions with decreased fertility.