In order to investigate the interaction of fresh and frozen–thawed
spermatozoa with oviduct epithelial cells, spermatozoa were co-incubated with
ovine oviduct epithelial cell monolayers (OECM) derived from either complete
oviducts, at any stage of the oestrous cycle (Experiments 1 and 2), or from
different regions of the oviduct at different stages of the cycle (Experiment
3). Fresh and frozen—thawed spermatozoa displayed different patterns
of binding to, and release from, the OECM. Frozen—thawed spermatozoa
immediately bound to the complete oviduct OECM and were released after 2 h. A
small proportion of fresh spermatozoa bound immediately, increasing to a
maximum after 2 h, and were gradually released thereafter. When only the cells
that were released from the OECM were observed by chlortetracycline staining
in Experiment 2, it was found that the presence of an OECM increased the
number of capacitated fresh spermatozoa while decreasing the number of
capacitated frozen–thawed spermatozoa. Overall, the OECM advanced the
membrane state of both types of spermatozoa from uncapacitated to
acrosome-reacted. Fresh and frozen—thawed spermatozoa bound to OECM
derived from the cells of the isthmus and the ampulla in similar proportions.
However, more spermatozoa were capacitated when incubated with OECM derived
from isthmic rather than ampullary cells. Higher proportions of fresh
spermatozoa bound to, and were acrosome-reacted following incubation with OECM
derived from post- rather than pre-ovulatory tracts. Such differences were not
observed for frozen—thawed spermatozoa. The findings reported in
this study show that fresh and frozen—thawed spermatozoa behave
differently when in contact with oviduct cells in vitro.
This may be a consequence of the more advanced membrane state of the frozen
spermatozoa upon thawing.
Morphological and functional characterization of bovine oviductal epithelial cell monolayers cultured on polarizing membranes
