Partial characterization of the gametes and development of a successful in vitro fertilization procedure in the mastomys (Praomys coucha): a new species for reproductive biology research

The mastomys, a small African rodent, has been extensively used as a laboratory animal for cancer research. Previous preliminary studies have demonstrated that the animal has a relatively short estrous cycle and that superovulation can be induced. However, biological characterization of the gametes in this species has not been done. The purpose of this study is to determine requirements for fertilization and to devise a suitable method for in vitro fertilization (IVF). Data from these studies show that 1) cauda epididymal plasma (CEP) is required for maintaining sperm motility in vitro; 2) in a heterologous sperm penetration assay in vitro, optimal conditions for sperm capacitation and the acrosome reaction depend on time and CEP concentration; and 3) loss of the cortical granules is observed to occur spontaneously within 3-4 h after ovulation in superovulated eggs. On the basis of the data obtained from these studies, we have developed a method for preincubation of mastomys sperm and a successful mastomys IVF procedure. This species can now be used as a new laboratory animal for research in reproductive biology.