Abstract
PURPOSE: To evaluate human sperm nuclear chromatin decondensation in a heterologous ICSI system using hamster ova injected with human sperm. MATERIALS AND METHODS: Frozen hamster oocytes were injected with Triton X-100 treated sperm and fixed at different time points post ICSI. Oocytes injected with non-treated sperm served as controls. Male pronuclear decondensation was evaluated after staining with DAPI. RESULTS: Sperm cells with partially destroyed membranes and depletion of the acrosome decondense more rapidly and to a greater extent than membrane/acrosome intact cells. Marked variability in pronuclear size was observed for any time point post ICSI, which most probably reflects the heterogeneity in the mature human sperm population. CONCLUSION: Remodeling of male gamete nuclei in this heterologous ICSI mimics events that occur during natural fertilization in humans and therefore this approach may be used for studies of human sperm chromosomes transformations.