Abstract
The lifetime reproductive performance of Mongolian gerbils from which an ovary had been removed 7 days before pairing at 100 days of age was only slightly inferior to that of normal females. A general decline in fertility was evident only in the oldest females. The mean number of litters, young born and age at last parturition were 7·6 ± 3·8, 37 ± 20 and 462 ± 196 days (2 ovaries) compared with 6·9 ± 3·5, 30 ± 16 and 417 ± 142 days (1 ovary) respectively.