What Occurs During Mating?
The queen will signal her willingness to mate with a unique posture: head down, forelegs bent, rear quarters raised to expose the vulva ( this raised posture is called lordosis), with the tail raised and held to the side of the body, all designed to accomodate entry by the tom cat's penis. Her rear legs will tread rhythmically, as if walking in place.
The tom cat will mount the female from the rear, holding her on the back of the neck with his teeth. This biting behavior may in part be to ensure cooperation, but may also stimulate a part of the female's brain that induces ovulation.
Whole male cats have barbed penises (much like a fishhook), and upon withdrawal, the female cat will often scream (whether from ecstasy or pain is questionable). It is also believed that the barbed penis stimulates ovulation. In fact, breeders sometimes use "Teaser Toms" to stimulate ovulation and end the estrus cycle in queens which are not yet ready for breeding. Teaser Toms are neutered by vasectomy, leaving the barbs on the penis to stimulate ovulation.