What are the common causes of necrospermia ?

Many cases of prolonged [url]azoospermia[/url] are a result of killing all the spermatogonial stem cells inside the testis by infection or other reasons that we do not know. In other instances, however, the stem spermatogonia survive but fail to differentiate into sperm. As is known, male infertility already had becomes one of the most difficult disease for men to solve. According to some dates, this disease can be caused by lots of factors and necrospermia is one of the most serious and important reason, but how necrospermia happens? What are the causes of necrospermia?