HORMONAL CONTROL OF SPERM PRODUCTION
To regulate the amount of sperm present at any time, the rate at which spermatogenesis occurs must be carefully controlled. Obviously this depends on a number of factors, including the sexual activity of the male. Spermatogenesis is hormonally regulated to ensure a well controlled sperm production. The hormonal mechanisms that regulate sperm production are based on the principle of negative feedback. In a negative feedback system, an increase in an element's output causes its production to decrease. One of the best ways to understand a negative feedback mechanism is to consider the operation of a thermostat that has been set to maintain room temperature at a certain degree. When the room cools below the set point, the thermostat causes the furnace to turn on and to produce heat, and when the room warms above the set point, the thermostat causes the furnace to shut off and to cease heat production. The various hormones involved in both the male and female reproductive systems function very much like the negative feedback mechanism of a furnace. The more we understand how these hormones ordinarily regulate reproduction, the more we will understand the workings of methods of birth control that interrupt these normal hormonal processes.