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Human Body Study

Intratesticular Ducts

The outflow plumbing inside the testis — the short stretch of ducts that collects sperm from the seminiferous tubules and delivers them to the epididymis. Three segments in sequence:

Schematic of the testis A labelled diagram of the testis. The left figure is a cut-away sagittal view showing the fibrous capsule (tunica albuginea), the septa dividing the testis into lobules, the coiled seminiferous tubules within each lobule, the mediastinum testis with its rete testis, the efferent ductules leaving the testis, the epididymis draped along its posterior border (head, body, tail), the vas deferens, and the spermatic cord with its testicular artery and pampiniform venous plexus. The centre figure is a magnified cross-section of a single seminiferous tubule with adjacent interstitium, showing tall Sertoli cells spanning the tubule wall, the spermatogenic lineage maturing from basement membrane to lumen, peritubular myoid cells, and Leydig cells in the interstitial space. The testis — cut-away and tubule cross-section scrotum mediastinum head body tail testicular artery pampiniform plexus vas deferens seminiferous tubule (cross-section) lumen capillary Scrotum & spermatic cord the skin sac that holds both testes outside the body,and the cord that suspends each testis carrying itsvessels, nerves, and vas deferens. Vasculature & nerves the testicular artery and the pampiniform venousplexus that cools it; lymphatics; autonomic nerves. Tunics & lobules the tough fibrous capsule (tunica albuginea), theserous outer tunica vaginalis, and the septa carvingthe testis into ~250 wedge-shaped lobules. Seminiferous tubules the tightly coiled tubes within each lobule wheresperm are made — about 250 m of tubule per testis. Intratesticular ducts straight tubules feed the rete testis (a networkin the mediastinum), which drains via efferentductules to the head of the epididymis. Sertoli cells tall nurse cells spanning the tubule wall;their tight junctions form the blood-testis barrier. Spermatogenic cells the germ-cell lineage, base to lumen — spermatogonia→ spermatocytes → spermatids → spermatozoa. Leydig cells endocrine cells between the tubules — thesource of testosterone, driven by LH. Interstitial tissue the loose stroma between tubules — capillaries,lymphatics, macrophages, and connective tissue. Left: sagittal cut-away of one testis with its epididymis and spermatic cord. Centre: magnified seminiferous tubule and adjacent interstitium. Not to scale.

Parts

Section titled “Parts”
  • Straight tubules (tubuli recti) — the terminal segment of each seminiferous tubule. At this point the wall changes character — the germ cells stop and the lining becomes Sertoli cells only, and then simple cuboidal epithelium — and the tube straightens out as it heads into the mediastinum.
  • Rete testis — a network of interconnecting channels lined by simple cuboidal/low-columnar epithelium, embedded in the fibrous tissue of the mediastinum testis (the posterior thickening of the tunica albuginea). Each straight tubule empties into this network, which mixes the outflow of all the lobules.
  • Efferent ductules (ductuli efferentes) — 12–20 small ducts that leave the rete testis, perforate the tunica albuginea at the upper pole, and curve out to fuse with the head of the epididymis. Their lining is unusual — alternating tall ciliated and short non-ciliated cells, giving the lumen a scalloped outline.

What they do

Section titled “What they do”
  • Collect and consolidate — the rete testis pools the output of all ~500 seminiferous tubules of one testis into a single drainage hub before sending it onward.
  • Resorb fluid — the efferent ductules reabsorb the bulk (~90%) of the tubular fluid that the Sertoli cells secreted. This concentrates the sperm dramatically, so what enters the epididymis is a thick suspension rather than a dilute stream.
  • Propel sperm — the cilia of the efferent ductule lining beat toward the epididymis, sweeping the now-concentrated sperm onward.

Where it sits in the sequence

Section titled “Where it sits in the sequence”
seminiferous tubule
   → straight tubule (tubulus rectus)
      → rete testis
         → efferent ductules
            → epididymis (head)
               → epididymis (body, tail)
                  → vas deferens → ejaculatory duct → urethra

The first three live inside the testis and form the subject of this page. The rest is the duct system of the broader male reproductive tract.

Key idea

Section titled “Key idea”

The intratesticular ducts are the funnel of the testis: they take the output of hundreds of seminiferous tubules, pool it in the rete, and dewater it on the way out so that a dilute factory stream becomes a concentrated stream of sperm by the time it crosses into the epididymis.