Evidence of sperm nuclear chromatin heterogeneity in ex-cryptorchid subjects

Ex-cryptorchid subjects are frequently affected by infertility, even if the usually determined seminal parameters are still within the normal range. We evaluated in this study, in 14 ex-unilateral cryptorchid adult males (22-28 years), with normal sperm concentration, morphology and viability, the resistance of sperm nuclear chromatin to denaturation, using the fluorochrome acridine orange, which fluorescences green when bound to native DNA (double stranded) and red when bound to denaturated DNA (single stranded). Our findings demonstrate that the percentage of green-stained cells with acridine orange was significantly lower in our patients than in controls (p less than 0.001). We therefore suggest that the chromatin of ex-cryptorchid subjects' spermatozoa has a decreased resistance to denaturation and we hypothesize that this finding may explain the infertility of these patients, when the common seminal parameters are still within the normal range.