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Histology - Proximal and Distal Tubules of Nephron

Proximal convoluted tubule, aka, PCT.
  • Bulging cuboidal/low columnar cells
  • Basal membrane has infoldings with their own mitochondria.
  • Microvilli that make up the brush border that fills the lumen; give the lumen a characteristic "fuzzy" appearance.
    • The basal membrane infoldings and brush border increase the surface area for diffusion; approximately 65% of reabsorption and secretion occurs within the PCT.
  • Lateral processes are cytoplasmic extensions that form lateral intercellular space; held together by intercellular junctions.
  • Large roundish euchromatic nucleus
    • It has several light-staining areas of euchromatin that reflect genome activity; know that the the dark-staining areas are heterochromatin, which comprises transcriptionally inactive portions of the genome.
  • Abundant mitochondria, which produce visible basal striations; mitochondria support the energetic requirements of the sodium-potassium pump, which plays a key role in resorption of water and nutrients from the PCT.
  • Abundance of dark-staining organelles, including the vesicles and mitochondria, give PCT cells a darker hue.
Distal convoluted tubule
  • Cuboidal and uniform cells
  • Lateral processes and intercellular junctions
  • Basal membrane infoldings
  • Luminal surface does not have a brush border, so the lumen appears wider and clearer than the PCT.
  • Euchromatic nuclei that they tend to lie close to the lumen, even bulging into it.
  • Numerous mitochondria and vesicles to support their high cellular activity, though not as much as the PCT; hence, these cells appear lighter in histological samples.
  • Macula densa is a tightly packed region of the DCT that lies near the renal corpuscle and afferent arteriole of the nephron.