It is given in Language of Medicine by Davy Ellen that from the ovumry of the woman a tube called fallopian tube goes towards the womb. Anywhere between the end of the second week or the beginning of the fourth week, an ovum is released. After intercourse, it is fertilized by sperm that enter the fallopian tube. Then the fertilized ovum travel through the fallopian tube and then the process of embryogenesis starts.
Due to some reasons, the sperm is not able to enter the fallopian tube and here IVF is used.
The diseases can be on the male side or on the female side.