Identification of a Receptor on the Vitelline Membrane of Bovine Oocytes that Recognizes Bovine Immunoglobulin G

¹ Department of Animal Science, University of Minnesota, St. Paul 55108

In order to investigate whether Ig molecules affect bovine fertility, bovine follicular oocytes were tested for an oolemmal receptor that recognized IgG. The zona pellucida was removed from 296 oocytes. The zona-free oocytes were then incubated with purified bovine IgG, its Fc fragment, or its Fab fragment. They were subsequently washed and incubated with the appropriate rabbit anti-bovine IgG (whole IgG-specific, Fc-specific, or Fab-specific), which was covalently attached to polyacrylamide beads (immunobeads). Bead attachment was scored using light microscopy. Bovine IgG and bovine IgG-Fc bound to the oocytes, whereas the IgG-Fab exhibited negligible binding. The data indicate that a bovine oolemmal receptor exists that binds IgG by recognizing the molecule in the region of the Fc-Fab junction. Thus, the binding of IgG or other Ig molecules to bovine oocytes may play a role in sperm and egg interaction.

Key Words: immunoglobulin • oocyte • receptor

Submitted on October 22, 1991
Accepted on February 3, 1992