SUMMARYThe absence of the acrosome causes the situation which is called globozoospermia. There are a few studies, mostly as case reports, about correlation between levels of sperm DNA damage in patients with total round-headed spermatozoa. We investigated this correlation as well as CMA3 positive spermatozoa in 20 globozoospermic men (with more than 90% round-headed spermatozoa) attending to Royan Institute. Semen samples divided into three parts to semen analysis, to measure DNA fragmentation index (DFI) using sperm chromatin structure assay (SCSA) and to detect CMA3 + sperm cells by chromomycin A3 staining and fluorescent microscopy. Our results showed that there were significant differences in sperm concentration, total sperm motility, and normal morphology between patients and controls group (p < 0.001). Moreover, the average of DFI and CMA3 positive spermatozoa in patients group significantly increases compared with control group (p < 0.001). A significant correlation between DFI and CMA3 + in total population was also detected in patients group (r = 0.45, p = 0.046). To our knowledge, this is the largest study about correlation between DNA damage levels and CMA3 positive spermatozoa with round head sperm cells in total globozoospermic men. It seems that the increase in DNA damage may be because of defective sperm DNA compaction, as we detected CMA3 positive sperm cells in these patients.

Sperm cryopreservation may lead to adverse effects on sperm structure and function. Cyanocobalamin (vitamin B12) has antioxidant potential and can protect DNA from free radical‐induced damages. Recent studies have shown that vitamin B12 preserves glutathione that leads to modulate oxidative stress responses. Also, vitamin B12 might act directly as a scavenger of ROS. The aim of this study was to investigate the effects of vitamin B12 supplementation on human sperm parameters during the cryopreservation process. Thirty semen samples were obtained from normozoospermic men. Using cryopreservation medium supplemented with different concentrations of vitamin B12 (0, 0.5, 1, 2, 2.5 mg/ml), the semen samples were cryopreserved. After thawing, all samples were evaluated for motility and viability. Based on results, 2 mg/ml was considered as the optimal concentration of vitamin B12 for evaluating sperm DNA fragmentation. The results showed that 1 and 2 mg/ml vitamin B12 significantly increased post‐thawing motility and viability compared with the 0 mg/ml vitamin B12 (p < .05). Also, by supplementing with 2 mg/ml vitamin B12, DNA fragmentation decreased when compared to the control. The present study showed that cryopreservation medium supplemented with vitamin B12 at 2 mg/ml could improve sperm quality after freeze–thaw process.