CorpusHuman Anatomy

Male Reproductive Organs

Midsagittal section — the path of sperm

A midsagittal view of the male pelvis and external genitalia, anterior to the left, with the urinary bladder, pubic symphysis, ureter and rectum shown for orientation. The testis in the scrotum makes sperm, which mature in the epididymis and travel up the ductus deferens within the spermatic cord, through the inguinal canal, over the ureter and down behind the bladder to the ampulla. There the duct joins the seminal vesicle to form the ejaculatory duct, which opens into the prostatic urethra. The urethra continues as the membranous part (through the external urethral sphincter, flanked by the bulbourethral glands) and the spongy part within the corpus spongiosum to the glans.

Animated sperm follow this route from testis to external urethral orifice, while yellow (seminal vesicle) and violet (prostatic) particles show the accessory gland secretions joining them. Note the prostate's position directly in front of the rectum, the basis of the digital rectal examination.

Step-by-step

  1. 1 · Spermatogenesis in the testis

    Sperm are produced in the coiled seminiferous tubules of the testis (≈64–74 days from spermatogonium to spermatozoon), supported by Sertoli cells, while interstitial Leydig cells secrete testosterone. The scrotum keeps the testes ≈2–3 °C below core temperature. Sperm leave through the rete testis and efferent ductules — still immotile.

  2. 2 · Maturation in the epididymis

    In the ≈6 m coiled duct of the epididymis (head → body → tail), sperm spend ≈10–14 days gaining progressive motility and the ability to bind the zona pellucida; fluid is reabsorbed and sperm are stored in the tail.

  3. 3 · Up the spermatic cord and through the inguinal canal

    The thick-walled ductus deferens ascends in the spermatic cord with the testicular artery and pampiniform plexus, passes through the superficial ring and inguinal canal, and leaves the cord at the deep inguinal ring, lateral to the inferior epigastric vessels. Vasectomy divides it in the scrotal part of the cord.

  4. 4 · Over the ureter to the ampulla

    In the pelvis the ductus runs over the lateral wall, crosses superior to the ureter ("water under the bridge") and descends on the back of the bladder, dilating into the ampulla, a short-term sperm reservoir lying medial to the seminal vesicle.

  5. 5 · Seminal vesicle and ejaculatory duct

    The ampulla joins the duct of the seminal vesicle to form the ejaculatory duct, which pierces the prostate to open on the seminal colliculus. During emission (sympathetic, T12–L2) the seminal vesicles add ≈60–70 % of semen volume: alkaline fluid rich in fructose, prostaglandins and semenogelins (yellow particles).

  6. 6 · Prostate and prostatic urethra

    The prostate adds ≈20–30 % of semen — thin, PSA-, citrate- and zinc-rich fluid — through ducts opening into the prostatic urethra. The internal urethral sphincter at the bladder neck contracts during emission so semen goes forward, not back into the bladder (retrograde ejaculation if it fails). The prostate lies directly in front of the rectum — hence the digital rectal examination.

  7. 7 · Membranous urethra and bulbourethral glands

    The membranous urethra — the shortest and narrowest part — passes through the external urethral sphincter. Beside it lie the pea-sized bulbourethral (Cowper) glands, whose ducts open into the bulb of the spongy urethra, releasing lubricating, alkaline pre-ejaculate.

  8. 8 · Spongy urethra and ejaculation

    The spongy urethra (≈15 cm) runs through the corpus spongiosum — whose thin tunica keeps it open during erection — to the external urethral orifice on the glans. Erection (parasympathetic NO → cGMP) fills the corpora cavernosa; ejaculation is a pudendal reflex in which bulbospongiosus contracts rhythmically to expel semen.

Labelled parts