What is infertility? How infertility is treated by assisted reproductive technologies like IVF-ET and ZIFT?

Explanation

Infertility: an woman who is unable to conceive is is called infertile. This infertility is caused due to defects in men of women or both.
Causes of infertility of menN:
* Deficiency of FSH and ICSH lead to diminished production of sperms.
* To maintian fertility, there must be 20 millions of sperms in 1 ml of semen but sterility is caused due to less number of sperms i.e., less than 10 millions in 1 ml of semen and it is called oligospermia.