Abstract
Present investigation was carried out to examine whether the loss of zona pellucida occurs in unfertilized eggs of mice during the estrous cycle and pseudopregnancy. A total of 1271 eggs were recovered from the oviducts and uterus by flushing with modified K.R.B. solution between 10:00 h on day 3 and 10:00 h on day 4 of the estrous cycle at 3 h intervals (day 1= day of estrus). Also 190 eggs were collected between at 5:00 h on the 4th day of pseudopregnancy and at 3:00 h on the following day at 2 h intervals. The percentage of unfertilized eggs without the zona pellucida were 2% (25/1271) in cyclic mice and 0.5% (1/190) in pseudopregnant mice.
