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Which cells produce testosterone in the testes?

A.

Sertoli cells

B.

Leydig cells

C.

Spermatogonia

D.

Myoid cells

Answer and Explanation

The Correct Answer is B

Leydig cells are interstitial endocrine cells located between the seminiferous tubules of the testes. They produce testosterone in response to luteinizing hormone (LH) from the anterior pituitary. Normal serum total testosterone levels in adult males range from 300–1,000 ng/dL. Testosterone is essential for development of male secondary sexual characteristics, maintenance of spermatogenesis, libido, and anabolic functions. LH secretion is regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus via negative feedback from circulating testosterone levels.

Rationale for correct answers

B. Leydig cells synthesize and secrete testosterone under LH stimulation. They are located in the interstitial space, separate from the seminiferous tubules where spermatogenesis occurs.

Rationale for incorrect answers

A. Sertoli cells are found within seminiferous tubules and support spermatogenesis by nourishing developing sperm and producing androgen-binding protein, not testosterone.

C. Spermatogonia are germ cells that undergo mitotic and meiotic divisions to produce spermatozoa, not steroid hormones.

D. Myoid cells are contractile cells surrounding seminiferous tubules, aiding movement of sperm and testicular fluid, but they do not produce hormones.

Take home points

  • Leydig cells are the testosterone-producing cells of the testes.
  • LH stimulates Leydig cells to secrete testosterone.
  • Sertoli cells support spermatogenesis but do not produce testosterone.
  • Spermatogonia are precursors of sperm, not hormone producers.


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Related Questions

Correct Answer is B

Explanation

Bulbourethral glands(Cowper’s glands) are paired exocrine glandslocated in the urogenital diaphragm, each draining into the proximal spongy urethra. They secrete an alkaline mucus-like pre-ejaculatory fluidthat neutralizes acidic urine residues in the urethra and lubricates the urethral lining. This secretion protects sperm during ejaculation by preventing acid-mediated damage and facilitating smooth passage. The alkaline pH (~7.4–8.0) of the secretion contributes to optimizing conditions for sperm viability during ejaculation.

Rationale for correct answers

B.The bulbourethral glands release alkaline mucus prior to ejaculation to neutralize urethral acidity and lubricate the passage for sperm.

Rationale for incorrect answers

A.Sperm are produced in the seminiferous tubules of the testes, not in bulbourethral glands.

C.Storage of mature sperm occurs in the tail of the epididymis, not in the bulbourethral glands.

D.Liquefaction of semen after ejaculation is mediated by PSA and other proteolytic enzymes from the prostate gland, not by bulbourethral glands.

Take home points

  • Bulbourethral glands secrete alkaline mucus before ejaculation.
  • Function is to neutralize urethral acidity and provide lubrication.
  • Sperm production and storage occur in the testes and epididymis respectively.
  • Prostate gland, not bulbourethral glands, liquefies semen post-ejaculation.

Correct Answer is B

Explanation

Seminal vesicle fluidis an alkaline secretion constituting about 60–70% of semen volume, rich in fructose, prostaglandins, and clotting proteins. Fructoseserves as the primary energy substrate for sperm motility by entering glycolysis within sperm cells. Normal seminal plasma fructose concentration is approximately 11–15 mmol/L. The alkaline pH (7.2–8.0) neutralizes vaginal acidity, enhancing sperm survival. Prostaglandins promote cervical mucus thinning and induce reverse peristalsis in the female reproductive tract to aid sperm transport.

Rationale for correct answers

B.Fructose in seminal vesicle fluid is the main nutrient metabolized by spermatozoa to generate ATP for motility and fertilization capability.

Rationale for incorrect answers

A.Glucose is not the predominant sugar in seminal vesicle fluid; while sperm can metabolize glucose, seminal vesicles specifically secrete fructose as their carbohydrate source.

C.Galactose is not a major component of seminal plasma; it is not secreted by seminal vesicles and has no primary role in fueling sperm.

D.Citrate is present in prostatic fluid, functioning mainly as a pH buffer and nutrient, but is not the main motility fuel in seminal vesicle secretion.

Take home points

  • Seminal vesicles secrete fructose as the primary sperm energy source.
  • Fructose concentration in seminal fluid can be a marker of seminal vesicle function.
  • Prostatic fluid contains citrate, not fructose.
  • Alkalinity of seminal fluid helps sperm survive in acidic vaginal environment.

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