COMPOSITION OF THE HUMAN ZONA-PELLUCIDA AND MODIFICATIONS FOLLOWING FERTILIZATION

The composition of individual human zonae pellucidae and modifications to this extracellular coat both before and after fertilization were a nalysed using a rapid, sensitive, non-radioactive biotinylation- or le ctin-based detection system; these assays use commercially available r eagents and can be performed on fragments of individual zonae pellucid ae. The zona pellucida from unfertilized eggs is composed of three gly coprotein species designated as huZP1, huZP2 and huZP3. Under non-redu cing conditions, the molecular weights of these proteins are similar t o 150 kDa, similar to 100 kDa, and similar to 55-65 kDa respectively. FoIlowing fertilization, huZP1 was not detected under either non-reduc ing or reducing conditions. In contrast, after fertilization huZP2 was detected under non-reducing conditions, but not under reducing condit ions. The ability to detect pre- and post-fertilization changes in a s ingle human zona pellucida is discussed in relation to its value in as sessing deficiencies in clinical and laboratory protocols used for in- vitro fertilization.