Applications of laser scanning confocal microscopy to the observation of human oocytes and embryos.

Laser scanning confocal microscopy (LSCM) is a powerful and useful tool in developmental biology. The diverse applications of LSCM in biomedical field has led to advances in the microscopes themselves and the synthesis of novel specific probes for the observation of biological structures and the hypothesis of physiological process. LSCM was used to visualize the cellular actin cortex together with the chromatin in human arrested preimplantation embryos and in unfertilized oocytes obtained by in vitro fertilization. In embryos, we observed a majority of multinucleated blastomeres and some with fragmented nuclei or anucleated. LSCM also showed nuclei displaying the chromatin condensation and fragmentation patterns suggesting the phenomenon of apoptosis. Moreover, in arrested fragmented embryos of poor morphology, unequal sized blastomeres often showed cellular fragments without nuclei, compatible with aspects of apoptotic bodies.