From Past to Present: An Historical Overview of the Concept of Spermatozoa, Reactive Oxygen Species, and Male-Factor Infertility

Abstract In this chapter we outline the history of reactive oxygen species (ROS) and spermatozoa, starting with some of the foundation experiments conducted by John MacLeod in 1943. Historically, we have seen that if ROS come into contact with spermatozoa in high enough concentrations, they trigger peroxidative damage that culminates in aldehyde by-products that are detrimental to cell function. This can be demonstrated in a number of ways, but for the most part, this has been achieved by external addition of ROS or exposure to ROS-generating in vitro systems. We also discuss the many challenges that await this field, including the various pitfalls associated with measuring ROS that make it difficult to ascertain if these metabolites are causally involved in the etiology of male-factor infertility or whether they are just playing a passive role. Today, with improved methods of measuring ROS, together with a better knowledge of the pathways associated with peroxidative damage, the involvement of oxidative stress on sperm function should become clearer.