Cleavage Rate of Mouse Eggs From Induced and Spontaneous Ovulation

Summary. The cleavage rate of mouse eggs was not affected by whether ovulation was spontaneous or induced, nor by the age of the mother, nor by the number of eggs shed, though spontaneously ovulated eggs were consistently about half a cleavage division less advanced than those from induced ovulation, suggesting that cleavage had begun about 5 hr later. The number of eggs recovered showed a significant decline from the 2nd to the 4th day of pregnancy in adult but not in immature mice.