Lactation following hysterectomy of pregnant mice

Hysterectomy of mice on Days 12–15 and on the 18th day of pregnancy induced lactation as assessed by weight gain of 1-day old foster young. Lactation did not develop following hysterectomy on the 10th and 11th day of gestation. Hysterectomy on Day 15 and Day 18 of pregnancy induced lactation performance similar to that of normally parturient mice whereas the lactation performance of aminals hysterectomized on Days 12–14 of pregnancy was inferior to that of normally parturient mice. Moreover, the later in pregnancy hysterectomy was performed, the sooner the mice began to lactate. Lactation was also exhibited when the presentation of foster young was delayed for 72 hours following hysterectomy on the 13th and the 18th day of gestation.