Permeability of the Mouse Zona Pellucida to Immunoglobulin

Reproductive Immunology Group, Department of Pathology, University of Bristol, University Walk, Bristol BS8 1 TD (Received 20th June 1974) During the preimplantation stages of pregnancy, the mammalian embryo is surrounded by an acellular envelope, the zona pellucida. Although little is known of the functions of this membrane it has been suggested that it may be impermeable to antibody molecules (immunoglobulins), thereby protecting the embryo from the potentially adverse effects of maternal immunity (Simmons & Russell, 1966, 1967). In the present study, we have investigated the permeability of the mouse zona pellucida to immunoglobulins by comparing the complementmediated cytotoxic effect of rabbit anti-mouse serum and two of its immunoglobulin components, IgG and IgM, on the development of zona-free and zona-enclosed embryos in vitro. Mouse embryos at the 8-cell stage were recovered in phosphate-buffered saline (PBS) from the oviducts of randomly bred hybrid mice 48 hr after the finding of a vaginal