Basic and Clinical Andrology is calling for submissions to our Collection on Sperm Motility. In mammals, sperm fertilization potential relies on efficient progression within the female genital tract to reach and fertilize the oocyte. This fundamental property is supported by the flagellum that provide the mechanical force for sperm propulsion and motility. As a result, structural and functional defects of the sperm flagellum are associated with impaired sperm motility, a condition called asthenozoospermia and predominant in human male infertility. In addition, as sperm flagella and motile cilia share an evolutionarily conserved microtubule structure, called the axoneme, male infertility can be evidenced in patients with Primary Ciliary Dyskinesia disease, which is mainly characterized by chronic lung, ear and sinus infections.
To date, little is known about the molecular and cellular events occurring in the late stages of spermatogenesis and underlying the dramatic morphological and structural changes of round spermatids to sperm cells with functional flagella. Considering that sperm flagella contain a specific set of axonemal components, which is distinct from that of motile cilia, and that they also harbor unique peri-axonemal structures (i.e., the mitochondrial sheath and the fibrous sheath), it is assumed that some mechanisms of sperm flagellum biogenesis are distinct from those involved in ciliogenesis. Recent advances in the genetics of male infertility due to severe morphological defects of the sperm flagella contributed in the identification of several genes that are essential for the biogenesis and/or stability of sperm flagella.
Importantly, although sperm cells that are produced in the testis are structurally differentiated, they remain immotile and are unable to fertilize the oocyte unless they undergo a series of maturation events that occur during their transit through the male and female genital tracts. It is now established that the micro-environments of the genital tracts (i.e., ion content, pH, metabolite and nutrient availability) trigger can sperm signaling pathways including protein phosphorylation cascades that are compulsory for sperm hyperactivation and fertilization potential.
In a clinical point of view, the management of asthenozoospermia only relies on assisted reproduction technologies and in particular intracytoplasmic sperm injection, which involves substantial medical procedures and economical costs. But the current research developed on several aspects of sperm motility from flagellum structure to functional activation events should help in the development of appropriated medical treatments for male infertility due asthenozoospermia. Recent advances also have identified potential and relevant targets for the development of specific male contraceptive methods without altering spermatogenesis. In this collection, we welcome researchers to submit their original research articles, reviews, or shorter perspective articles on all aspects related to the theme of “Sperm motility”, in both animal models and in humans.