Recent researches on mammalian spermatozoa

In mammalian testes, spermatogonia are distributed in the basal part of seminiferous tubules and proliferate mitotically. Some of them undergo the processes of meiosis and spermiogenesis, and then differentiate into spermatozoa. However, spermatozoa are still functionally immature in the testes and gradually acquire the potential to move progressively and fertilize oocytes during the transit through the epididymis. After ejaculation into female reproductive tract, spermatozoa undergo a variety of physiological and morphological changes including capacitation, flagellar hyperactivation and acrosome reaction, and finally achieve fertilization with oocytes in the ampulla of the oviduct. Recently, basic studies of these research fields are making rapid progress by using cell biological and molecular biological methods, especially techniques of gene manipulation. Meanwhile, although several decades have already passed since practical application of the artificial insemination using cryopreserved semen in mammals (cattle), there are recent problems of subfertility in both males and females which result in lowering productivity of the offspring (calves). In order to overcome these problems, the applied studies have made a significant achievement in the development of reproductive biotechnology. On this page, five RMB-invited review articles which are related to the basic and applied studies on mammalian spermatozoa (including male germ cells) are introduced as Editor's choice. My hope is that they would be helpful for the improvement of clinical activities as well as activities of basic researches and animal industries.
Editor, Hiroshi Harayama