CBSE Class 10 Answered

Azoospermia is the absence of spermatozoa in the semen or the failure of formation of spermatozoa. It can arise as a result of primary testicular failure, obstruction or previous vasectomy. Complete azoospermia signifies infertility.

Common causes of azoospermia include:

Primary testicular failure - This may be due to genetic defects, undescended testes, physical injury to the testes or mumps occurring after puberty. Often the cause is unknown.

Obstruction - Sexually transmitted diseases may cause epididymitis and lead to blockage of the ductal system, resulting in permanent azoospermia. Obstructive azoospermia can also be due to agenesis (absence) of the epididymis and other parts of the ductal system, including the vas deferens. Some of these cases seem to be of genetic origin.

Previous vasectomy - This is an increasingly common cause of azoospermia in Western countries and in countries such as India where it is a favoured method of contraception.

Absence of germ cells - In many men with azoospermia, the seminiferous tubules contain only Sertoli cells. This can result from numerous causes, including cytotoxic drugs, irradiation or due to factors present during foetal life. However, in most cases the aetiology is unknown.