Bovine oviductal epithelial cells (BOEC) and oviducts: I. For embryo culture. II. Using SEM for studying interactions with spermatozoa.

The oviduct (uterine tube) plays a major role in reproduction. It is a dynamic organ which selectively permits a few sperm to undergo capacitation and reach the oocyte which has continued to undergo maturation following ovulation. Then following fertilization the embryo undergoes cleavage before arriving in the uterus. Extensive information has become available from in vitro studies on oocytes as well as spermatozoal interactions with oviductal cells. Bovine oviduct epithelial cell (BOEC) monolayers with simple media provide an environment in which zygotes can be cultured to blastocysts in 6 days with cell numbers essentially equivalent to blastocysts grown totally in the donor animal. These yield normal pregnancy rates upon transfer. The simple protein-free media currently under test hold promise for elucidating specific requirements of the preimplantation embryo and these defined conditions facilitate many related studies on in vitro fertilization and genetic engineering of embryos. The second part of this paper is an extensive study on the interaction of fresh and frozen-thawed bull spermatozoa with BOEC and segments of intact oviducts as viewed by SEM. Both types of oviductal cells were incubated at 39 degrees C for 0, 3, 6, and 9 hours, using material obtained from periovulatory cows. Sperm attached immediately to both types of epithelium and reached a peak at 3 hours. They were found primarily in the furrows of the intact oviducts. Secretory droplets appeared rapidly on the anterior portion of the sperm head and acrosomal changes were evident in 3 hours, similar to those reported in vivo. Changes were more rapid with frozen-thawed sperm.