[Germ cell transplantation as a tool for fertility preservation of oncological patients]

Spermatogonia are the diploid cells in the testis, representing a small self-sustaining pool of male germ line stem cells as well as a larger pool of differentiating germ cells which enter the process of spermatogenesis. After going through prophase of meiosis as spermatocytes these cells finally leave the testis as sperm. Spermatogonia share many characteristics with other stem cells but also carry some specific physiological features. Many details about the kinetics of spermatogonial divisions, about the hormonal regulation of their expansion and differentiation and about their clinically relevant involvement as a cause for male infertility are poorly understood. However, the loss of spermatogonia following chemo- or radiotherapy leading to temporary or permanent infertility of the patient is a well known and unwanted site effect of many oncological therapies. Isolation and extracorporal storage of spermatogonia prior to the treatment and transplantation into the testis after recovery from the disease presents a promising future tool for fertility preservation in male patients undergoing oncological therapy.