Comparison of intrabursal transfer of spermatozoa, a new method for artificial insemination in mice, with intraoviductal transfer of spermatozoa.

PURPOSE

The objective of this paper was to compare the in vivo fertilizing abilities of fresh epididymal spermatozoa with a new method of artificial insemination in mice, so-called "intrabursal transfer of spermatozoa (ITS)," which requires transfer of spermatozoa into a space near the infundibulum between the ovary and ovarian bursa of superovulated females, and the previous method, so-called "intraoviductal transfer of spermatozoa (IOTS)," especially as regards sperm number and capacitation.

METHODS

Spermatozoa freshly isolated from B6C3F1 males were injected into superovulated B6C3F1 females on E 0.4 (10:00 AM) by the IOTS or ITS method. Embryos at two-cell stage were collected from the females 1 day after injection and their morphology was scored. Some females were allowed to survive at midgestational stages and inspected for development of normal fetuses.

RESULTS

When 1 microL of a sperm suspension containing uncapacitated 1 x 10(5) spermatozoa freshly isolated from B6C3F1 males was injected by the IOTS or ITS method, normal two-cell embryos were recovered from the females at rates ranging from 14 to 23% with each method. This rate was much lower than that (93% on average) for embryos obtained by natural mating. Neither injection of 1 x 10(3) or 1 x 10(4) spermatozoa nor induction of capacitation improved in vivo fertilization rate. In both cases, females given spermatozoa exogenously yielded midgestational fetuses (E 12.5-13.5) with average litter sizes between 2.5 and 2.8.

CONCLUSION

ITS was comparable to IOTS with the conditions used. These two methods will be valuable for artificial insemination in mice for propagation of offspring from particular transgenic or mutant lines that are difficult to breed, although further attempts to improve in vivo fertilization ability are required.