Of course these chemical messages are produced by both genders and are species specific. Pheromones are composed of carbon compounds that form volatile organic acids. Women's pheromones waft and can be detected at some distance. Once received, pheromones have two types of effects. There is the releaser effect that precipitates an immediate change in the behavior of the recipient.
Some pheromones produce a very strong and immediate effects while others engender very little.
Dr. Wedekind's experiment involved tee shirts worn by 44 men for two days. Sexual behavior involves the entire nervous systems of the participants. Both the autonomic nervous system, which controls involuntary sexual responses such as erection, lubrication, increased breathing and heart rates as well as well as the somatic nervous system, which is involved with sensory information and voluntary actions, are both fully engaged. Afferent loops are formed between the sensory information being relayed from the skin, genitalia, etc. along the spinal cord to the brain. While the sexual activity is an expected consequence of pheromone releaser and primer effects there are subtler effects as well.