Biochemical and biophysical changes in the hamster Zona pellucida following egg activation

Following fertilization and cortical granule release, the mammalian zona pellucida (ZP) undergoes changes associated with the block to polyspermic fertilization and the protection of the developing embryo. These changes are not well understood and may vary among species. We have begun a multidisciplinary study of these changes in the golden hamster. Electrical activation, which stimulates cortical granule exocytosis, decreased binding of capacitated sperm to the ZP. Application of the medium from activated eggs to fresh eggs and/or capacitated sperm decreased subsequent sperm-ZP binding without altering sperm motility or viability. Activation produced a slightly decreased susceptibility to ZP digestion by 0.01% trypsin over the 3 hrs. following activation. No comparable change in susceptibility to 0.0015 M 2-mercaptoethanol was observed. Biomechanical properties of the ZP were measured using a capillary suction technique. In contrast to ZP 'hardening' with respect to trypsin digestion, activation produced no change in ZP elasticity. In summary, activation significantly reduces hamster sperm-ZP binding without producing large changes in ZP resistance to either chemical digestion or mechanical deformation.

Duke Scholars

Author David F. Katz Biomedical Engineering