The Mammalian Egg’s Block to Polyspermy
The eggs of most mammals at ovulation are metabolically relatively inert cells arrested in metaphase II of meiosis. In response to an activation stimulus normally provided by the fertilizing sperm but induced artificially by a number of parthenogenetic agents, the egg resumes meiosis, undergoes a cortical reaction, and becomes metabolically more active. Visible evidence for the resumption of meiosis involves the abstriction of a second polar body at approximately 30 min postactivation. In the cortical reaction, the egg undergoes the exocytotic release of its cortical granules, a process that results in formation of a new mosaic plasma membrane from the fusion of limiting cortical granule membranes with the egg plasma membrane. At the same time, cortical granule contents released into the perivitelline space come in contact with the egg plasma membrane and the zona pellucida. The cortical reaction and granule exocytosis are of primary interest to any discussion of polyspermy for cortical granule contents have been associated with polyspermy-preventing mechanisms in the eggs of animals of diverse species (for review, see Schuel, 1978, or Gulyas, 1980).
KeywordsZona Pellucida Cortical Granule Perivitelline Space Zona Hardening Cortical Reaction
Unable to display preview. Download preview PDF.
- Eager, D. D., Johnson, M. H., and Thurley, K. W., 1976, Ultrastructural studies on the surface membrane of the mouse egg, J. Cell Sci. 22:345–353.Google Scholar
- Gould, K., Zaneveld, L. J. D., Srivastava, P. N., and Williams, W. L., 1971, Biochemical changes in the zona pellucida of rabbit ova induced by fertilization and sperm enzymes, Proc. Soc. Exp. Biol. Med 136:6–10.Google Scholar
- Gwatkin, R. B. L., Fertilization Mechanisms in Man and Mammals, Plenum Press, New York.Google Scholar
- Hanada, A., and Chang, M. C., 1972. Penetration of zona-free rat eggs by spermatozoa of different species, Biol. Reprod. 6:300–309.Google Scholar
- Oh, Y. K., and Brackett, B. G., 1975, Ultrastructure of rabbit ova recovered from ovarian follicles and inseminated in vitro, Fertil. Steril. 26:665–685.Google Scholar
- Okamoto, H., Takahashi, K., and Yamashita, N., 1977, Ionic currents through the membrane of the mammalian oocyte and their comparison with those in the tunicate and sea urchin, J. Physiol. 267:465–495.Google Scholar
- Pienkowski, M., 1974, Study of the growth regulation of preimplantation mouse embryos using concanavalin A, Proc. Soc. Exp. Biol Med. 145:464–469.Google Scholar
- Repin, V. S., and Akimova, I. M., 1976, Microelectrophoretic analysis of protein composition of zonae pellucidae of mammalian oocytes and zygotes, Biochemistry (USSR) 41:39–45.Google Scholar
- Schmell, E. D., and Gulyas, B. J., Ovoperoxidase activity in ionophore treated mouse eggs. II. Evidence for the enzyme’s role in hardening the zona pellucida, Gamete Res. 3:279.Google Scholar
- Solter, D., 1977, Organization and the antigenic properties of the egg membrane, in: Immunobiology of Gametes (M. Edidin and M. H. Johnson, eds.), Cambridge University Press, London, pp. 207–234.Google Scholar
- Yanagimachi, R., 1977, Specificity of sperm-egg interactions, in: Immunobiology of Gametes (M. Edidin and M. H. Johnson, eds.), Cambridge University Press, London, pp. 255–295.Google Scholar