CorpusHuman Anatomy
ReproductiveOrgan part

Seminiferous tubules

Tubuli seminiferi contorti

Also known as: seminiferous epithelium, convoluted seminiferous tubules

Highly coiled tubules that make up ≈80–90 % of the testis, lined by a stratified epithelium of Sertoli cells and developing germ cells in which spermatogenesis takes place.

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Overview

Each testis contains several hundred convoluted seminiferous tubules (≈150–250 µm in diameter), each tens of centimetres long and looped so that both ends open into the rete testis via straight tubules. The seminiferous epithelium is unusual: tall Sertoli cells extend from the basement membrane to the lumen, and between them lie germ cells at progressively later stages from the base (spermatogonia) towards the lumen (spermatocytes, spermatids, then released spermatozoa).

Tight junctions between Sertoli cells divide the epithelium into a basal compartment (spermatogonia, accessible to blood-borne substances) and an adluminal compartment (spermatocytes and spermatids, behind the blood–testis barrier). Outside the basement membrane, flattened contractile peritubular myoid cells generate peristaltic waves that move fluid and the non-motile sperm towards the rete testis. Spermatogenesis proceeds in a coordinated "wave", so neighbouring segments of a tubule show different cell associations (stages).

Location

Lobules of the testis, between the septa of the tunica albuginea, draining to the rete testis in the mediastinum.

Anatomy

Histology

Stratified seminiferous epithelium of Sertoli cells and spermatogenic cells; thick basement membrane; 3–5 layers of peritubular myoid cells; lumen containing spermatozoa and fluid.

Function

  • Site of spermatogenesis.
  • Secretion of tubular fluid (by Sertoli cells) that carries sperm to the rete testis.
  • Transport of immotile sperm by peritubular myoid contraction.

Clinical significance

Testicular biopsy patterns

In non-obstructive azoospermia, biopsy may show Sertoli-cell-only syndrome (no germ cells), maturation arrest or hypospermatogenesis; microdissection TESE can retrieve sperm for ICSI in some men. Germ-cell neoplasia in situ, the precursor of germ-cell tumours, arises along the tubule basement membrane.

Compiled from standard anatomy and physiology references — see the Reproductive System sources. For education only; not medical advice.