A subpopulation of morphologically normal, motile spermatozoa attach to equine oviductal epithelial cell monolayers.

This study focuses on the bond between spermatozoa and oviductal epithelial cells (OEC) in horses, suggesting that the sperm that attaches to the OEC layer comprise a specific subset with higher motility and morphological normality compared to the overall semen.

Hypothesis and Methodology

The researchers hypothesized that the sperm, which tapes onto equine OEC monolayers, represent a handpicked portion of the whole semen. They assumed this subpopulation to contain a greater percentage of morphologically typical, motile cells than the originally inseminated semen itself.

To test their hypothesis, the researchers selected washed stallion sperm and cocultured them with monolayers of OEC or Vero cells. They also maintained control samples, which were settled in wells layer with basement membrane extract (Mgel) or in plastic uncoated wells. After half an hour of coculture, the sperm cells that did not attach were removed by rinsing.

Data Collection

Sperm that attached and then released were gathered after 3 hours. After incubation, they counted the total cell numbers and percentages of motile, viable, and morphologically normal spermatozoa in the initial inseminate, plastic control wells, and the coculture supernatants.

The percentages of motile and morphologically standard sperm bound to OEC, Mgel control wells, and Vero cell cocultures were also measured at 0.5 and 3 hours of incubation.

Results

The study’s results indicated that sperm populations that bound to either OEC or Mgel exhibited higher motility and those attached to OEC contained a more elevated percentage of normal sperm than the inseminate. Compared to the inseminate, populations that did not attach maintained similar viability and contained a similar percentage of normal sperm but exhibited lower motility. The sperm populations released after 3 hours showed a similar percentage of normal morphology to those attached but displayed reduced motility and viability when compared to the inseminate.

Conclusion

There was no discernible difference in motility or morphology between sperm populations that bound to OEC and those that attached to Vero cell monolayers. This finding suggests that it is the OEC and Mgel surfaces themselves that may select a specific subpopulation of sperm cells with improved mobility and structural normality.