RESUMEN
PURPOSE: This study was performed to evaluate chromatin condensation of morphologically mature sperm using a modified aniline blue-eosin (AB-E) staining method in azoospermia. MATERIALS AND METHODS: Chromatin condensation was analyzed using an AB-E staining method in 61 cases (50 patients) of TESE or testicular biopsy with the patient's own sperm. Obstructive azoospermia (OA) was present in 48 cases in 39 patients and non-obstructive azoospermia (NOA) was present in 13 cases in 11 patients, respectively. Immature sperm heads were stained dark blue, whereas mature sperm were stained red-pink by the eosin. The percentage of sperm chromatin condensation was calculated from the ratio of the number of red-pink sperm to the total number of sperm analyzed. RESULTS: The percentage of chromatin maturity was 37.7% vs. 30.3% in OA and NOA, respectively, of the total sperm cell count. The maturity of fresh testicular sperm was 38.3% and 36.3% in OA and NOA, respectively. Also, the maturity of thawed testicular sperm was 34.5% and 10.3% (p<0.05) in OA and NOA, respectively. The maturity of fresh and thawed testicular sperm was 36.3% and 10.3% (p<0.05), respectively, in NOA. These results suggest that chromatin condensation is less stable in sperm of NOA and freezing and thawing procedures may impair sperm chromatin condensation. CONCLUSIONS: In our results, the aniline blue-eosin staining method improved the visualization of excessive histones in sperm and the diagnosis of sperm immaturity in morphologically normal testicular sperm. We found that AB-E staining method can be an effective method for analyzing testicular sperm chromatin condensation in azoospermia.