Caspase-3 detection in human testicular spermatozoa from azoospermic and non-azoospermic patients

The apoptotic mechanisms underlying spermatogenesis in testis are poorly understood. In the present study, the rates of testicular spermatozoa with active caspase-3 were quantified in testicular samples with normal and impaired spermatogenesis. Testicular spermatozoa were collected from 18 men after testicular biopsy during assisted reproductive treatments: five presented oligozoospermia, four congenital bilateral absence of the vas deferens (CBAVD), five secondary obstructive azoospermia (sOAZ) and four hypospermatogenesis. Ejaculated samples were derived from six normozoospermic patients. Testicular spermatozoa were analysed using a fluorescence microscope and differences among groups were calculated using regression logistic models. Total rates of spermatozoa with active caspase-3 were significantly higher in sOAZ (78.6±13.9), followed by hypospermatogenesis (70.8±5.8), CBAVD (55.9±25.5), oligozoospermia (31.7±31.0) and normozoospermia (20.4±15.5). Distinct patterns of active caspase-3 were observed in testicular spermatozoa compartments: midpiece, equatorial region, acrosomal vesicle region, nucleus and cytoplasm. Hypospermatogenesis showed active caspase-3 mainly in the midpiece. In CBAVD, sOAZ and oligozoospermia, active caspase-3 was mainly in the nucleus, although no differences were found between oligozoospermia and hypospermatogenesis. In sOAZ, active caspase-3 in the spermatozoa nucleus was 1.89-fold higher than in CBAVD. Results suggest that tubular obstruction may induce nuclear lesions and that disrupted spermatozoa production observed in cases of hypospermatogenesis might be associated with mitochondrial lesions.