To the Editor:
We read with interest the recent article by Mahfouz et al. (1), and we have some observations.
First, the authors concluded that after semen processing, “the incidence of late apoptotic sperm remains unchanged.” This finding is not consistent with previous studies (2,3) and our recent report (4). The authors found the percentage of non-necrotic sperm (PI negative sperm) to be 63.1% in neat semen and 66.9% after density-gradient separation. In other words, the semen processing provided a sample with one third of PI positive (necrotic) sperm. Thus, assuming that necrotic sperm are immotile, the mean motility after semen processing was less than 67%. This is a surprising result, since the efficiency of density-gradient separation is usually much higher. In fact, the authors report that the sperm motility was significantly improved in all the samples after density-gradient separation. In our recent study, we found a significantly lower percentage of necrotic sperm in the capacitated fraction (8.4%) compared with neat semen (13.1%). Read the rest of this entry »
