Spermatogenesis arrest is known as the interruption of germinal cells of specific cellular type, which elicits an altered spermatozoa formation. Spermatogenic arrest is usually due to genetic factors resulting in irreversible azoospermia. However some cases may be consecutive to hormonal, thermic, or toxic factors and may be reversible either spontaneously or after a specific treatment. Spermatogenic arrest results in either oligospermia or azoospermia in men. It is quite a difficult condition to proactively diagnose as it tends to affect those who have normal testicular volumes; a diagnosis can be made however through a testicular biopsy. Effects Spermatogenic arrest results in either oligospermia or azoospermia as mentioned above. Oligospermia is when extremely low concentrations of fertile sperm are found in semen or ejaculate, while azoospermia is when no fertile sperm are found in the semen or ejaculate. Causes Spermatogenesis is controlled by androgens, namely testosterone and follicle-stimulating hormone (FSH), these are the most important androgens that control the process. FSH uses very specific G-coupled receptors that can be found only on Sertoli cells, this hormone is secreted by the pituitary gland, located in the brain. While testosterone, is produced within the testicles by Leydig cells. This hormone is the main androgenic steroid in the process of spermatogenesis and is regulated by a hormone known as luteinizing hormone. FSH plays a role in the spermatogenic capacity of the adult male as it controls the proliferation of Sertoli cells during either the perinatal or pubertal period, or both. However, testosterone has been found to be the most important hormone that is responsible for both the initiation and the maintenance of spermatogenesis. It is known that spermatogenesis is under the control of androgens, but germ cells (that will become gametes), do not express a functional androgen receptor, which are activated by the binding of androgenic hormones. It has been found through studies that spermatogenetic arrest tends to occur in the late spermatocyte/spermatid stage when the androgen receptor activation in Sertoli cells is interrupted or affected in some way. However, other studies have found that the condition can be due to either genetic factors or a variety of secondary factors. Chemotherapy When using chemotherapy treatments, the possibility of azoospermia is dependent on the dose, duration, number and type of drugs used; the male's fertility status before the treatment occurred is also taken into consideration. Radiotherapy The use of radiotherapy can cause a temporary bout of