At the onset of puberty, the hypothalamus causes the release of FSH and LH into the male system for the first time. FSH enters the testes and stimulates the Sertoli cells to begin facilitating spermatogenesis using negative feedback, as illustrated in Figure 1. LH also enters the testes and stimulates the interstitial cells of Leydig to make and release testosterone into the testes and the blood. Figure 1. Hormones control sperm production in a negative feedback system. Testosterone , the hormone responsible for the secondary sexual characteristics that develop in the male during adolescence, stimulates spermatogenesis.
Secondary sex characteristic
Female secondary sex characteristics
Puberty is the stage in life when a child's body develops into an adult's body. The changes take place gradually, usually between the ages of 10 and Changes occur at puberty because of hormones :. The menstrual cycle is a recurring process which takes around 28 days. During the process, the lining of the uterus is prepared for pregnancy. If pregnancy does not happen, the lining is then shed.
[Mechanism on onset of secondary sexual characteristics in the female]
Secondary sex characteristics are features that appear during puberty in humans , and at sexual maturity in other animals. Secondary sex characteristics include, for example, the manes of male lions ,  the bright facial and rump coloration of male mandrills , and horns in many goats and antelopes. These characteristics are believed to be produced by a positive feedback loop known as the Fisherian runaway produced by the secondary characteristic in one sex and the desire for that characteristic in the other sex. Male birds and fish of many species have brighter coloration or other external ornaments.
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