Normally, each ejaculate of semen contains nearly 60 to 120 million sperms with a normal head-neck-tail structure. They swim forward rapidly towards the egg. However, only one sperm fuses with the ovum at the end.
Problems in Semen:
At times sperms are not present in the semen. The reasons for this could be many:
Difficulties in Intercourse:
Due to impotence or failure of ejaculation, or ejaculation in a wrong direction, the semen cannot be deposited in the vagina thus causing infertility. The quality of semen may be normal in these cases if collected by other artificial methods.
Infection in the Semen:
Sometimes the semen sample is found to be infected with certain bacteria, thus hindering fertilization.