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USMLE® Step 1 questions

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USMLE® Step 1 style questions USMLE

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A researcher studies the development of the male genitalia in utero. Which of the following hormones is directly responsible for the differentiation of the epididymis during the intrauterine period?  

External References

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testosterone/methyltestosterone for p. 681

5 α-reductase

testosterone conversion p. 652


testosterone/methyltestosterone p. 681

Hypothalamus p. 512

exogenous testosterone effect p. 652


testosterone and p. 652

Luteinizing hormone (LH)

testosterone p. 681

Testosterone p. 652, 682

androgen insensitivity syndrome p. 663

cryptorchidism p. 675

Klinefelter syndrome p. 661

Leydig cell secretion p. 653

pharmacologic control p. 679

Sertoli cells p. 652

SHBG effect on p. 353

signaling pathways for p. 353

spermatogenesis p. 652

Testosterone-secreting tumors p. NaN

Testosterone synthesis p. 196


When someone mentions testosterone, it might conjure up images of a burly alpha male.

That’s because testosterone, the primary male hormone, is an androgen, andro meaning male and gen meaning “to produce”, which means testosterone helps generate the characteristics associated with male sexuality.

The effects of testosterone are first seen in the fetus.

During the first six weeks of development, the reproductive tissues of males and females are identical,

but in week seven, genes in the sex-determining region of the Y chromosome initiate the development of testicles.

Once they form, the fetal testicles secrete testosterone which guides development of the male urogenital tract and external genitalia,

as well as testicular descent through the inguinal canal which happens in the last two months of fetal development.

The fetal ovaries also secrete testosterone but at much lower levels, and this largely explains the differences in fetal development between boys and girls.

In puberty, the hypothalamic-pituitary axis takes center stage in regulating testosterone levels and gonadal function - which are the testes in young men.

The hypothalamus secretes gonadotropin-releasing hormone which moves through the bridge between the hypothalamus and the pituitary gland, called the hypothalamo-hypophyseal portal system, and gets to the anterior lobe of the pituitary.

In response, the anterior pituitary secretes luteinizing hormone and follicle-stimulating hormone - two gonadotropic hormones which get secreted into the blood and reach the gonads.


Testosterone is the primary male sex hormone and an anabolic steroid. In men, it plays a key role in the development of male reproductive tissue and secondary sexual characteristics. It is produced mainly in the testes and is responsible for several functions, including sexual differentiation during fetal life, and the development of primary sexual characteristics like an enlarged penis and testes, as well as secondary characteristics like a male pattern of hair growth, voice changes, and various anabolic effects.


  1. "Medical Physiology" Elsevier (2016)
  2. "Physiology" Elsevier (2017)
  3. "Human Anatomy & Physiology" Pearson (2018)
  4. "Principles of Anatomy and Physiology" Wiley (2014)
  5. "Biological Actions of Androgens" Endocrine Reviews (1987)
  6. "The benefits and risks of testosterone replacement therapy: a review" Therapeutics and Clinical Risk Management (2009)
  7. "Testosterone, Bone and Osteoporosis" Frontiers of Hormone Research (2008)

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