Dear Colleagues,

When insemination occurs, millions of spermatozoa enter the female reproductive tract with a single aim – to find and reach a single cell - the oocyte. Spermatozoa subsequently undertake an adventurous journey leading to their encounter with the oocyte, thereby initiating a series of cellular interactions that culminate in fertilization. Understanding the cellular, sub-cellular and molecular mechanisms that underpin the structural integrity of sperm and their functional activity prior to fertilization is crucial. This should allow the development of diagnostic strategies to help elucidate the etiologies of male sub- or infertility, as well as the identification of novel targets for fertility regulation. In this special issue, we will discuss recent advances on the physiology of spermatozoa, molecular pathways regulating sperm behavior, risk factors affecting sperm functionality, and the contribution of spermatozoa to fertility outcomes. In addition, we will review different pharmacological agents and biomolecules that may improve sperm quality under in vitro and in vivo conditions in order to improve the outcomes from assisted reproductive technology (ART). We hope this special issue will help clinicians, andrologists, toxicologists, and embryologists to understand the factors that influence sperm quality in health and disease, as well as the development of various management strategies to improve treatment outcomes.

Dr. Eva Tvrda
Guest Editor