A typical day of microinjection at most institutions involves the injection of upwards of 200 embryos. Typically between 7 and 10 animals are superovulated to yield sufficient embryos for one day's microinjection. Additionally you will require the same number of male stud animals to mate to the superovulated females. Male stud animals should be used no more than twice weekly, and tracked as to their ability to plug females. For the embryo recipient mice, a colony large enough to consistently produce sufficient animals in estrus for each day's injection effort is required.
Planning involves knowing the length of estrus cycle for the strain used for embryo recipients.
In order to vaginally plug these animals a stud colony of vasectomized males is required. These should be monitored for their ability to plug estrus females. It is recommended that a strain with a different coat color is used for embryo recipient animals and vasectomized studs than used for the embryo donors for microinjection, to allow easy detection of any vasectomized male that may have re-ligated a vas deferens and regained fertility. The ability of the intended embryo donor strain to be superovulated should be considered, as some strains do not react well to gonadotropin treatment. Hybrid strains tend to respond well and produce substantially higher egg yields than by natural matings, although some inbred strains have a consistently good performance also.