What Hormones Do the Testes Produce? A Complete Cell-by-Cell Map

Six major signaling molecules drive testicular function, including testosterone, dihydrotestosterone, estradiol, androstenedione, inhibin B, and anti-Müllerian hormone. Testosterone from Leydig cells drives muscle growth, bone density, libido, and voice deepening, while Sertoli cells inside the tubules release inhibin B and AMH to regulate the pituitary and guide fetal development.

You’ll get a cell-by-cell map of every hormone your testes make, the brain-testes feedback loop that keeps them in balance, and the lab values that turn vague symptoms into a specific conversation with your doctor.

The Testes Function as Both a Reproductive and Endocrine Organ

Sperm don’t appear out of nowhere, and neither do the hormones that travel through your bloodstream. Inside each testicle, two microscopic neighborhoods handle separate jobs and sit almost back-to-back. Sperm are built inside tightly coiled tubes, while hormones enter the blood from the loose tissue wrapped around those tubes. Neither neighborhood works well without the other, because spermatogenesis depends on the high local testosterone concentration the surrounding tissue creates.

That pairing is why the testes qualify as a dual-function organ. They generate sperm as a reproductive gland, and they secrete hormones directly into circulation as an endocrine gland. The Endocrine Society, the professional body that studies hormone-secreting organs, classifies the testes among the body’s major endocrine tissues for this exact reason.

Two Cell Types, Two Different Jobs

The cells responsible for sperm production live inside the seminiferous tubules, which make up roughly 80–90% of testicular volume. Sertoli cells line these tubules and act as nursemaids to developing sperm, but they also release hormones of their own. Outside the tubules, in the loose interstitial tissue between them, sit Leydig cells. These round cells specialize in one thing: secreting steroid hormones, primarily testosterone, into nearby capillaries.

So when someone says “the testes produce testosterone,” the more accurate statement is “Leydig cells in the interstitial tissue produce testosterone,” and the same precision applies to every other hormone made in this organ.

Why Most People Only Hear About Testosterone

Testosterone dominates the cultural conversation because its decline produces visible changes in energy, muscle mass, and sex drive. Hormone-replacement marketing has also trained the public to think of it as the only male hormone worth tracking. The reality is that Sertoli cells release at least two other hormones (inhibin B and anti-Müllerian hormone) that are clinically meaningful, and Leydig cells release smaller amounts of estradiol and dihydrotestosterone alongside testosterone.

None of these are trivia; each shapes a different part of male physiology.

Leydig Cells and the Family of Androgens They Secrete

Leydig cells sit in the connective tissue between seminiferous tubules and respond directly to luteinizing hormone (LH) from the pituitary. Once stimulated, they convert cholesterol into testosterone through a multi-step enzymatic pathway, releasing the finished hormone into both the bloodstream and the local testicular fluid. Normal adult Leydig cells produce roughly 4–7 mg of testosterone per day, a number that stays surprisingly steady in healthy young men and gradually falls with age.

Testosterone itself is the headline androgen, but it’s not the only one these cells make. Androgens are a broader category of hormones that bind androgen receptors and drive masculine development, and several members of that family originate in the testes or from testicular hormones converted elsewhere in the body.

The Androgens That Originate in the Testes

DHT is roughly 2–5 times more potent at the androgen receptor than testosterone itself, which is why even a small amount has outsized effects on the prostate and hair follicles. Estradiol, which most people associate with female biology, is a legitimate Leydig output and a clinically important male hormone. About 20–30% of male estradiol comes directly from Leydig cells; the rest comes from aromatase enzymes converting testosterone in fat, muscle, and brain tissue.

Why Androgens Are Not Interchangeable

Because testosterone, DHT, and estradiol act on different receptors in different tissues, a man with “normal” total testosterone can still have symptoms if DHT conversion runs too high (acne, hair loss) or too low (poor libido, incomplete puberty). A simple total testosterone test misses most of this nuance, which is one reason experienced clinicians order additional labs when symptoms persist despite a “normal” reading.

Sertoli Cells Produce the Non-Androgen Hormones of the Testes

Inside the seminiferous tubules, Sertoli cells cradle each developing germ cell from spermatogonium to mature spermatozoon. To coordinate this work, they secrete a small but essential set of peptide hormones (short protein-based signals rather than steroids) that tell the brain how the tubules are doing and shape fetal sexual development before puberty even begins.

Sertoli hormones don’t duplicate androgen effects. They handle complementary jobs: regulating follicle-stimulating hormone (FSH) output from the pituitary, guiding fetal sexual differentiation, and supporting germ cell maturation through the blood-testis barrier.

The Hormones Sertoli Cells Release

• ▸Inhibin B: the main feedback signal Sertoli cells send to the pituitary to suppress FSH secretion, especially active in adult men.
• ▸Anti-Müllerian Hormone (AMH): produced at high levels during fetal life to regress the Müllerian ducts (the structures that would otherwise develop into female reproductive organs), then later serves as a marker of Sertoli cell number in pediatric and fertility evaluations.
• ▸Activin: a supporting signal that generally promotes FSH release and modulates Sertoli cell function, balancing inhibin’s effects.
• ▸Other growth factors: smaller secretions that maintain the blood-testis barrier and coordinate germ cell development.

Notice how each of these hormones targets a different audience. Inhibin B talks to the pituitary. AMH talks to developing fetal tissue before birth. Activin fine-tunes the balance. Together, they form a control layer that androgens alone cannot provide.

How Sertoli Hormones Complement Androgens

Testosterone creates the high local environment inside tubules that sperm need to mature. Sertoli hormones tell the rest of the body, especially the brain, how efficiently that work is proceeding. A drop in inhibin B is often the earliest detectable sign that sperm production is struggling, sometimes appearing years before testosterone or sperm counts fall.

The Hypothalamic-Pituitary-Gonadal Feedback Loop in Plain Language

Production of these hormones doesn’t run on a freewheel. A constant conversation between the brain and the testes, called the hypothalamic-pituitary-gonadal (HPG) axis, adjusts output up or down based on demand, stress, sleep, and circulating hormone levels.

The circuit has three stations: the hypothalamus (a small brain region just above the pituitary), the pituitary gland (a pea-sized gland at the base of the brain), and the gonads (your testes). Each station listens to the others and responds accordingly.

The Signaling Cascade, Step by Step

1. 1GnRH from the hypothalamus: the hypothalamus releases gonadotropin-releasing hormone (GnRH) in pulses every 60–120 minutes.
2. 2LH and FSH from the pituitary: GnRH triggers the pituitary to release LH (which targets Leydig cells) and FSH (which targets Sertoli cells).
3. 3Hormone production in the testes: LH drives testosterone secretion from Leydig cells; FSH supports inhibin B secretion and sperm maturation in Sertoli cells.
4. 4Negative feedback to the brain: rising testosterone suppresses LH release from the pituitary and slows GnRH pulses; rising inhibin B suppresses FSH specifically.

This is why clinicians rarely order testosterone alone. A testosterone level only tells you the end of the chain. Adding FSH and LH reveals whether the problem lies in the testes (primary hypogonadism, marked by low testosterone with high LH/FSH) or in the brain (secondary hypogonadism, marked by low testosterone with low or normal LH/FSH).

The Circadian Pattern Most Labs Miss

“Testosterone peaks between roughly 7–9 a.m. and falls by 20–30% by evening, so a single blood draw at 4 p.m. can falsely suggest low production.

For accurate assessment, fasting morning blood draws between 8 and 10 a.m. are standard practice. Two separate draws on different days are often ordered before confirming low testosterone, because daily variation, illness, poor sleep, and alcohol can all suppress a single reading.

Why the Less-Known Hormones Matter for Male Health

Focusing only on testosterone misses several important health connections. The “minor” testicular hormones often carry signals that testosterone alone cannot.

Estradiol, for instance, isn’t a leftover from female biology. Male bones require estradiol to maintain density, and the brain uses estradiol to support mood, memory, and libido. Men whose estradiol drops too low (often from over-aggressive testosterone treatment) can develop hot flashes, joint aches, and depressive symptoms, even when testosterone reads “normal” or “high.”

Clinical Uses of Each Non-Testosterone Hormone

• ▸Inhibin B: a direct marker of Sertoli cell function and a predictor of sperm production; low values in a fertility workup suggest primary testicular failure even when testosterone looks fine.
• ▸Anti-Müllerian Hormone (AMH): high in boys before puberty and used to evaluate testicular presence and function in pediatric endocrinology; in adults, it helps assess Sertoli cell function in men with infertility.
• ▸Estradiol: essential for bone density, libido, and brain function; low levels may explain bone loss, fatigue, and sexual dysfunction in men on aromatase-inhibiting treatments.
• ▸DHT: critical for external genital development in utero; in adults, useful in evaluating unusual hair loss patterns or prostate symptoms.

Patterns Worth Noticing

Certain lab combinations flag specific issues. High FSH and LH alongside low testosterone means the testes are failing despite strong brain signaling, pointing toward primary hypogonadism. Normal or low FSH and LH with low testosterone means the brain is the weak link, suggesting secondary hypogonadism. High FSH with normal testosterone but poor sperm count means Sertoli cells are struggling while Leydig cells still work fine.

Each pattern changes the conversation with your doctor, which is why a panel beats a single value.

Recognizing Imbalance and Knowing When to Seek Evaluation

Hormone imbalance in men rarely produces one dramatic symptom. It usually shows up as a cluster of slow changes that are easy to blame on aging, stress, or poor sleep. Spotting the pattern matters because some causes, such as a pituitary tumor or undiagnosed testicular damage, are treatable when caught early.

Low testosterone is the imbalance people hear about most, but imbalance can also show up as elevated FSH, low inhibin B, low estradiol, or unusual combinations, depending on which cells are affected.

Common Signs Worth Tracking

• ▸Fatigue that persists for weeks: especially when sleep and stress haven’t changed.
• ▸Reduced libido or erectile changes: a gradual drop that doesn’t track with mood or relationship factors.
• ▸Loss of muscle mass with increased body fat: particularly around the midsection, despite consistent exercise.
• ▸Mood shifts or brain fog: new irritability, low motivation, or trouble concentrating that lasts beyond a few weeks.
• ▸Bone or joint complaints: unexpected fractures or persistent achiness can flag low estradiol, not just low testosterone.
• ▸Infertility or abnormal semen analysis: often the first and only sign of Sertoli cell trouble.

These symptoms overlap heavily with thyroid disease, depression, sleep apnea, medication side effects, and ordinary aging. That overlap is precisely why lab testing, not guesswork, matters.

Practical Steps and Common Mistakes

When you suspect hormone imbalance, a morning fasting blood draw between 8 and 10 a.m. covering total testosterone, free testosterone, LH, FSH, estradiol, and sometimes inhibin B gives the clearest initial picture. Repeating an abnormal result on a different day rules out short-term variation from poor sleep, illness, or alcohol.

If results come back normal but symptoms persist, a specialist such as an endocrinologist or urologist can order additional workup, including prolactin, thyroid studies, semen analysis, or imaging if the picture warrants it.

Mistake: relying on a single testosterone result without timing, repeat testing, or supporting labs. Mistake: assuming symptoms are “just aging” without ruling out reversible hormone causes. Mistake: attributing fertility problems to testosterone when the real issue is Sertoli cell function, which inhibin B and FSH together reveal. Above all, avoid self-prescribing testosterone or any hormone-related supplement without lab confirmation and clinical guidance, because raising one hormone can quietly drop another.

The Big Picture

The testes produce at least four distinct hormones, each from a specific cell type, each with a different audience. Leydig cells make testosterone, smaller amounts of estradiol, and androgen precursors; Sertoli cells make inhibin B and AMH. Production runs on a brain-testes feedback loop, with LH, FSH, inhibin, and testosterone themselves serving as the signals. Knowing which cell makes which hormone, and which lab value to ask about, turns vague symptoms into a specific conversation with your doctor.

FAQ