LH, Leydig cells and testosterone in male puberty
In male puberty, luteinising hormone (LH) from the pituitary gland stimulates Leydig cells, which sit between the sperm-producing tubules of the testes, to make testosterone from cholesterol.
Remember
LH drives the Leydig cells to make testosterone from cholesterol, while follicle-stimulating hormone (FSH) acts on the Sertoli cells instead, the supporting cells that nourish developing sperm.
Male puberty runs along a chain from the brain to the testes. The hypothalamus (the part of the brain that controls the pituitary gland) releases gonadotrophin-releasing hormone (GnRH) in pulses, and during puberty these pulses are strongest overnight. GnRH makes the anterior pituitary (the front part of the pituitary gland) release LH and FSH.
In the testis, LH binds to receptors on the Leydig cells. These cells sit in the interstitium (the tissue between the coiled seminiferous tubules, where sperm are made) and convert cholesterol into testosterone. Because LH release is highest at night, testosterone rises through the night and peaks in the morning.
The tubules contain germ cells (the cells that divide and mature into sperm) and the Sertoli cells, the supporting cells that nourish the developing sperm. FSH acts on the Sertoli cells, so it supports sperm production rather than testosterone synthesis. The Sertoli cells also release inhibin, a hormone that restrains FSH.
The rising testosterone drives the secondary sexual characteristics (the physical changes of puberty, such as pubic hair growth and penile enlargement). A simple way to remember the pairs is that LH goes with Leydig, and FSH goes with Sertoli and sperm.
Key facts
- LH target
- the Leydig cells in the interstitium of the testes, which make testosterone from cholesterol.
- FSH target
- the Sertoli cells inside the seminiferous tubules, which support developing sperm.
- GnRH
- acts on the anterior pituitary to release LH and FSH, not directly on the testes.
- Overnight rise
- GnRH pulses are strongest overnight in puberty, so LH and then testosterone rise through the night, and testosterone is highest in the morning.
- Pulse pattern
- continuous GnRH exposure suppresses LH and FSH release instead of stimulating it.
- Testosterone effects
- in boys it causes growth of the penis and muscle, deepening of the voice and denser pubic and armpit hair.
Exam traps
- Follicle-stimulating hormone (FSH) is a genuine puberty hormone, but it does not stimulate the Leydig cells: its target in the testis is the Sertoli cells, which support sperm production, while Leydig cells respond to LH.
- Gonadotrophin-releasing hormone does not act directly on the testes to release testosterone: it stimulates the anterior pituitary to release LH and FSH, and LH then acts on the Leydig cells.
- Inhibin is made by the Sertoli cells, not the Leydig cells, and it selectively inhibits FSH rather than LH.
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