title: Absence of an electrical polyspermy block in the mouse.
abstract: To examine the possibility of an electrical polyspermy block in the mouse, we recorded the electrophysiological properties of zona-free mouse eggs during fertilization. Starting from an unfertilized value of -41 +/- 4 mV (SD), the membrane potential undergoes an oscillation (seen in 8 of 11 records) of 4 +/- 1 mV in amplitude, starting 7 +/- 5 min after insemination, and lasting about 1 min. However, except for this small oscillation, the membrane potential is constant during the 60 min following insemination; the average range (11 +/- 4 mV) is not significantly different from that which is observed in 60-min recordings from unfertilized eggs. These results indicate that the polyspermy block which is established during this period (D. P. Wolf, 1978, Dev. Biol. 64, 1-10) is not electrically mediated. Consistent with this finding, reduction of the sodium or calcium concentration in the external medium does not induce polyspermy. As a consequence of fertilization, the resistance of the egg membrane decreases from 96 +/- 34 to 44 +/- 15 M omega; this change accompanies the voltage oscillation.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D004553:Electric Conductivity; D005260:Female; D005306:Fertilization / Q000187:drug effects; D008564:Membrane Potentials; D051379:Mice; D009994:Osmolar Concentration; D010063:Ovum / Q000502:physiology*; D012964:Sodium / Q000494:pharmacology; D015044:Zona Pellucida / Q000502:physiology
chemical_list: D012964:Sodium; D002118:Calcium