Sperm-oviduct interaction: Induction of capacitation and preferential binding of uncapacitated spermatozoa to oviductal epithelial cells in porcine species

After mating, inseminated spermatozoa are transported to the oviduct. They attach to and interact with oviductal epithelial cells (OEC). To investigat e sperm-OEC interactions, we used chlortetracycline to study the capacitati on status of boar spermatozoa in coculture with homologous OEC and cells of nonreproductive origin (LLC-PK1, porcine kidney epithelial cell line). Boa r spermatozoa were cocultured with OEC and LLC-PK1 cells for 15, 60, 120, o r 240 min. The proportion of capacitated spermatozoa in coculture with the isthmic and ampullar cells increased significantly (p < 0.05) during incuba tion. However, most spermatozoa in coculture with LLC-PK1 cells or blank (m edium only) remained uncapacitated. In addition, preferential binding of un capacitated, capacitated, or acrosome-reacted boar spermatozoa to OEC and t he other cell type was investigated. Our approach was to vary the proportio ns of uncapacitated, capacitated, or acrosome-reacted boar spermatozoa in s uspension using long preincubation and lysophosphatidylcholine treatment of semen prior to a very short incubation with OEC or LLC-PK1 cells. The resu lts showed that the majority of spermatozoa that were bound to OEC or LLC-P K1 cells were uncapacitated and that a significant relationship existed bet ween the relative proportion of uncapacitated spermatozoa in the control sa mples and those bound to LLC-PK1 cells (r(2) = 0.43, p < 0.005). However, t here was no correlation between the proportion of uncapacitated spermatozoa in the control samples and the proportion of those bound to isthmic or amp ullar cells. In conclusion, the results clearly demonstrated the specific nature of the sperm-OEC interaction in the porcine species. This interaction is initiated by uncapacitated spermatozoa binding to OEC and is continued by the induct ion of capacitation in cocultured spermatozoa.