**12. Concluding Remarks**

Redox regulation plays a major role in controlling sperm functionality, recent research is unveiling the existence of sophisticated redox regulation systems that may constitute targets for the treatment of the male factor subfertility. In addition, the interaction between metabolism and redox regulation may offer alternatives to traditional methods of sperm conservation. The increasing use of proteomic techniques in research in spermatology will provide significant advances in the understanding of redox regulation in the spermatozoa in coming years.

**Funding:** The authors received financial support for their studies from the Ministerio de Economía y Competitividad-FEDER, Madrid, Spain, gran<sup>t</sup> AGL2017-83149-R and the Junta de Extremadura-FEDER (IB16030 and GR18008).

**Conflicts of Interest:** The authors declare that there is no conflict of interest that may affect the impartiality of the information presented in this paper. "The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results".
