**2. Conclusions**

From the above-mentioned information, it can be concluded that intense sperm selection occurs in the vagina and that sperm mobility and rheotaxis are the determinant factors on the basis of which sperm selection in the vagina and sperm uptake in SSTs takes place. Sperm are capable of agglutinating in motile bundles having distinctive motility behaviors making them capable of clinging to adjacent surfaces. In the lumen of SSTs, sperm agglutinate in stationary bundles which prolongs sperm storage duration. Sperm gradually detach from the agglutinated sperm bundle and egress from the SSTs to ascend the oviduct and fertilize the ova. Therefore, sperm agglutination influences paternity outcomes when sperm from different males are present in a competitive situation because sperm bundles from males with a high tendency of sperm agglutination will remain in the SSTs for longer durations, and this gives them increased opportunities to fertilize more ova.

## **Acknowledgements**

The authors would like to acknowledge funding from the School of Veterinary Medicine and Science, University of Nottingham.

## **Author contributions**

 The work was divided equally among the authors. Mohamed. A. M. Sayed, Hanan H. Abd-Elhafeez, and Taymour M. El-Sherry, including the research study, data analysis and interpretation, and figure creation. Mohamed. A. M. Sayed, Hanan H. Abd-Elhafeez, Taymour M. El-Sherry, and Catrin. S. Rutland all contributed towards writing the chapter. All authors have read and approved the final version of the book chapter.

## **Conflict of interest**

The authors declare no conflict of interest.
