The interaction of fresh and frozen-thawed ram spermatozoa with oviducal epithelial cells in vitro

Abstract

In order to investigate the interaction of fresh and frozen-thawedspermatozoa with oviduct epithelial cells, spermatozoa were co-incubated withovine oviduct epithelial cell monolayers (OECM) derived from either completeoviducts, at any stage of the oestrous cycle (Experiments 1 and 2), or fromdifferent regions of the oviduct at different stages of the cycle (Experiment3). Fresh and frozen—thawed spermatozoa displayed different patternsof binding to, and release from, the OECM. Frozen—thawed spermatozoaimmediately bound to the complete oviduct OECM and were released after 2 h. Asmall proportion of fresh spermatozoa bound immediately, increasing to amaximum after 2 h, and were gradually released thereafter. When only the cellsthat were released from the OECM were observed by chlortetracycline stainingin Experiment 2, it was found that the presence of an OECM increased thenumber of capacitated fresh spermatozoa while decreasing the number ofcapacitated frozen-thawed spermatozoa. Overall, the OECM advanced themembrane state of both types of spermatozoa from uncapacitated toacrosome-reacted. Fresh and frozen—thawed spermatozoa bound to OECMderived from the cells of the isthmus and the ampulla in similar proportions.However, more spermatozoa were capacitated when incubated with OECM derivedfrom isthmic rather than ampullary cells. Higher proportions of freshspermatozoa bound to, and were acrosome-reacted following incubation with OECMderived from post- rather than pre-ovulatory tracts. Such differences were notobserved for frozen—thawed spermatozoa. The findings reported inthis study show that fresh and frozen—thawed spermatozoa behavedifferently when in contact with oviduct cells in vitro.This may be a consequence of the more advanced membrane state of the frozenspermatozoa upon thawing.