Although artificial insemination is a critical tool for
reproductive biologists working with other species (including
humans), it is not often used by mouse geneticists. Its major
use in other species is to initiate a successful pregnancy when,
for any of a number of reasons, the male cannot or should not,
be directly involved in the process of mating. Artificial
insemination has been a boon to the cattle industry because the
semen from one good bull can be shipped around the world to
impregnate unlimited numbers of females. Male mice are somewhat
smaller than bulls and, as a consequence, the whole animal can
be shipped for a cost that is likely to be the same (or less)
than one would pay for frozen semen alone. Furthermore,
obtaining semen from a mouse is a "one-shot" deal. Since
assisted masturbation of the male mouse is not practical, sperm
must be recovered from the epididymis after the animal has been
sacrificed. There are some special cases where artificial
insemination can be used as an experimental to