Home Education AUAUniversity Education Products & Resources Pathology for Urologists Normal Histology and Important Histo-anatomic Structures Kidney: Tubules and Collecting Ducts

Kidney: Tubules and Collecting Ducts

Image A

Image B

Proximal (PCT) and distal (DCT) convoluted tubules

  • Function to reabsorb ~75% of glomerular filtrate (PCT) and sodium ions from tubular fluid (DCT).
  • Histology:
    • PCT has abundant dark-pink cytoplasm (mitochondria) with prominent brush border (increased surface area for reabsorption) (image A) & (image B).
    • DCT has smaller cells with less cytoplasm, which gives the impression of "more nuclei" in cross-section.

Image C

Image D

Loop of Henle (LH)

  • Produces increasing osmotic gradient from cortex to deepest medulla.
  • Thin descending limb: simple squamous epithelium (image C).
  • Thick ascending limb: low cuboidal epithelium.

Collecting tubules (CT)

  • No active reabsorptive function.
  • Form medullary rays of kidney.
  • Cuboidal epithelium without brush border.

Collecting ducts (CD)

  • Convey urine to the pelvicaliceal space.
  • No active reabsorption unless ADH is present (then cells become permeable to water which is passively reabsorbed).
  • Tall columnar cells with well-defined cellular outlines (largest form the Ducts of Bellini) (image D).