The Male pill is a colloquial term for a male oral contraceptive. It has been in development since the 1960s and is not yet available for public consumption. It functions similarly to the female oral contraceptive known colloquially as the Pill: both use synthetic hormones to alter the body's chemical balance and prevent the maturation of gametes, so that the woman does not ovulate (though she may still menstruate) and the man's semen does not contain sperm. Unlike the female pill, the male pill packs (if/when sold) may not contain placebos, since the male reproductive system is not cyclical in nature. Furthermore, all known substances that inhibit spermatogenesis (such as gossypol) inflict unacceptable side effects, resulting in the male pill's continued unavailability. Some groups (Pill For Men (http://www.pillformen.com)), however, believe an FDA-approved version may be available as soon as 2005.