ABSTRACT
Fertilization of an oocyte by a sperm to form a zygote triggers a series of morphological changes, including extrusion of the second polar body and the development and gradual migration of the male and female pronuclei. Using polarization microscopy, it became possible to examine spindle dynamics, detect spindle morphology, predict chromosome misalignment, monitor thermal control, and perform spindle transfer. Although the results of these studies are sometimes contradictory, a meta-analysis of 10 trials determined that oocytes with a spindle detectable by polarization microscopy show higher rates of fertilization and faster rates of cleavage and embryo development up to the blastocyst stage. Characterization of the architecture of the zona pellucida of human oocytes with polarization microscopy revealed an association between the birefringence of the inner layer and the developmental potential of an oocyte.
