Hormonal Control of Spermatogenesis: GnRH, FSH and LH
Biology · Human Reproduction · NEET
Spermatogenesis is controlled by a hormone chain. At puberty the hypothalamus releases GnRH, which makes the anterior pituitary secrete two gonadotropins: LH and FSH. LH acts on the Leydig cells to make androgens (testosterone) that drive sperm formation, while FSH acts on the Sertoli cells. Memory hook: "GnRH is the boss, LH goes to Leydig, FSH goes to Sertoli" - both start with the same letter sound, so pair L-L and the odd one FSH to Sertoli.
Hormone axis of spermatogenesis: GnRH (hypothalamus) makes the anterior pituitary release LH and FSH. LH goes to Leydig cells (androgens), FSH goes to Sertoli cells - together they drive sperm formation.
Your doubts, answered
Does LH or FSH act on the Leydig cells?
LH acts on the Leydig cells. LH stimulates the Leydig (interstitial) cells to make and secrete androgens like testosterone. These androgens then drive spermatogenesis. This is a very common NEET point: LH goes to Leydig, not FSH. In NEET 2024 an assertion said FSH acts on Leydig cells - that statement was marked FALSE for this exact reason.
Which hormone acts on the Sertoli cells, FSH or LH?
FSH acts on the Sertoli cells. NCERT states clearly: FSH acts on the Sertoli cells and stimulates them to secrete factors that help the process of spermiogenesis (changing spermatids into sperms). So remember: FSH to Sertoli, LH to Leydig. Do not swap them.
Does GnRH act on the anterior or posterior pituitary?
GnRH acts on the anterior pituitary gland, not the posterior. GnRH is a hypothalamic hormone. It reaches the anterior pituitary and makes it release LH and FSH. The posterior pituitary only stores oxytocin and vasopressin, so any option pairing GnRH with the posterior pituitary or with oxytocin is wrong (this was the NEET 2017 trap).
What are the two gonadotropins that GnRH stimulates?
GnRH stimulates the anterior pituitary to secrete two gonadotropins: Luteinising Hormone (LH) and Follicle Stimulating Hormone (FSH). Both are needed for full sperm production. If an option lists oxytocin or relaxin instead of LH or FSH, it is incorrect.
When does hormonal control of spermatogenesis begin?
It begins at puberty. Before puberty GnRH is low, so sperm are not made. At puberty GnRH secretion rises sharply, which raises LH and FSH, and spermatogenesis starts. This is why sperm formation is not seen in childhood.
What is the role of androgens in spermatogenesis?
Androgens (mainly testosterone) are made by the Leydig cells after LH stimulation. These androgens then directly stimulate the process of spermatogenesis inside the seminiferous tubules. So the chain is: LH to Leydig cells to androgens to spermatogenesis.
⚠️ The NEET trap ✗ FSH acts on the Leydig cells (interstitial cells) in males. ✓ FSH acts on the Sertoli cells. It is LH that acts on the Leydig cells to secrete androgens. 🧠 NEET 2024 put this in an Assertion-Reason. Students who swap the two cells lose the mark. Fix it forever: FSH-Sertoli, LH-Leydig.
Real NEET questions
2017
GnRH, a hypothalamic hormone, needed in reproduction, acts on
A · Anterior pituitary gland and stimulates secretion of LH and oxytocin
B · Anterior pituitary gland and stimulates secretion of LH and FSH ✓
C · Posterior pituitary gland and stimulates secretion of oxytocin and FSH
D · Posterior pituitary gland and stimulates secretion of LH and relaxin
Solution: GnRH is a hypothalamic hormone that acts on the ANTERIOR pituitary gland and stimulates secretion of the two gonadotropins, LH and FSH. Options naming the posterior pituitary, or oxytocin/relaxin, are wrong because the posterior pituitary only releases oxytocin and vasopressin and does not respond to GnRH.
2024
Assertion A: FSH acts upon ovarian follicles in female and Leydig cells in male. Reason R: Growing ovarian follicles secrete estrogen in female while interstitial cells secrete androgen in male human being.
A · Both A and R true but R is NOT the correct explanation of A
B · A is true but R is false
C · A is false but R is true ✓
D · Both A and R are true and R is the correct explanation of A
Solution: Reason R is TRUE: growing follicles secrete estrogen in females and interstitial (Leydig) cells secrete androgens in males. Assertion A is FALSE: FSH acts on ovarian follicles in females, but in males FSH acts on the SERTOLI cells, not the Leydig cells. It is LH that acts on the Leydig cells. So A is false but R is true.
Solved Human Reproduction NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
What is the full hormone pathway of spermatogenesis?
Hypothalamus releases GnRH to anterior pituitary. Anterior pituitary releases LH and FSH. LH acts on Leydig cells to make androgens; androgens drive spermatogenesis. FSH acts on Sertoli cells to help spermiogenesis.
Which hormone directly stimulates androgen secretion in males?
LH (Luteinising Hormone) directly stimulates the Leydig cells to synthesise and secrete androgens like testosterone.
Is GnRH a hormone from the pituitary?
No. GnRH is made by the hypothalamus. It travels to the anterior pituitary and controls the release of LH and FSH.
Why does spermatogenesis start only at puberty?
Because GnRH secretion rises significantly at puberty, which then raises LH and FSH levels and switches on sperm production.
What does FSH stimulate the Sertoli cells to do?
FSH stimulates Sertoli cells to secrete factors that help spermiogenesis, the step where spermatids are changed into mature spermatozoa.
