Vasectomizing a Mouse

Vasectomized males are needed to engender pseudopregnancy in mature female mice. Such pseudopregnant females act as hormonally and physiologically competent recipients for microinjected fertilized one-cell eggs (see Chapter 20 ). Vasectomized males retain their sexual potency and leave a copulatory plug after mating, but, of course, fail to transmit any sperm. Some laboratories use genetically sterile males for this purpose rather than mice rendered sterile by surgery.