Correlation between testicular mast cell count and spermatogenic epithelium in non-obstructive azoospermia

Although there is emerging evidence that mast cells are involved in infertility, their exact role has not been elucidated clearly. Here we carried out a retrospective case-control study to find out whether there is a correlation between mast cell (MC) count and proliferation (Ki67 index) of the spermatogenic epithelium as well as of the Sertoli cells (vimentin-positive) in non-obstructive azoospermia (NOA). We assessed MCs, Ki67 and vimentin expression in Sertoli cells in testicular biopsies of germ cell aplasia (GCA, n = 14) and maturation arrest (MA, n = 14) vs. normal spermatogenesis (n = 14) cases. There was a significant decrease in the spermatogonial Ki67 index (1.25 ± 0.91, 4.21 ± 1.81 vs. 39.57 ± 3.92) and Johnsen score (2.48 ± 0.65, 4.89 ± 1.05 vs. 9.75 ± 0.30) as well as a significant increase (P < 0.001) in MC count (29.00 ± 4.11, 7.57 ± 1.95 vs. 3.00 ± 1.30) in seminiferous tubules of infertile cases with GCA and MA vs. controls. On the other hand, the percentage of vimentin-expressing Sertoli cells was significantly decreased (P < 0.001) in biopsies of cases with MA (35.50 ± 15.62) compared to those of cases with GCA and controls (72.64 ± 10.67 and 98.57 ± 1.45 respectively). Additionally, a significant negative correlation was detected between MC count and Ki67 index as well as Johnsen score in the MA group which became more significant in the GCA group. The significant increase in MC count in the GCA group and to a lesser extent in the MA group indicates their possible role in NOA particularly at the spermatogonial proliferation level and this is supported by the significant negative correlation with the Ki67 index.