Demonstration of pulmonary vascular perfusion by electron and light microscopy

M F König, J M Lucocq, E R Weibel

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34 Citations (Scopus)


To estimate the fraction of dense pulmonary capillary network that is perfused under physiological conditions, we developed a new method for the demonstration of in vivo capillary perfusion by light and electron microscopy. Blood plasma was labeled by 8-nm colloidal gold particles coated with rabbit serum albumin. In anesthetized rabbits, 4-5 ml of this tracer were injected into the right atrium. Two and 15 min later, the circulation was interrupted by a snare around the heart, and the lung was fixed by instillation with glutaraldehyde. Gold particles were found in the plasma space of alveolar capillaries as well as in other organs. A random sample of thin sections studied by electron microscopy revealed that the entire capillary bed of the lung was perfused at least with plasma within 2 min after tracer infusion. Light microscopy of silver-enhanced sections showed areas with different staining intensities but no obviously unperfused capillaries. The concept of capillary recruitment, which would require a significant fraction of capillaries unperfused at rest, may have to be reassessed to consider time factors as well as the two-phase nature of blood; red blood cells and plasma may take different paths.
Original languageEnglish
Pages (from-to)1877-83
Number of pages7
JournalJournal of Applied Physiology
Issue number4
Publication statusPublished - Oct 1993


  • Animals
  • Capillaries
  • Endocytosis
  • Gold
  • Lung
  • Lung Volume Measurements
  • Microscopy, Electron
  • Microspheres
  • Paraffin Embedding
  • Rabbits
  • Serum Albumin
  • Spectrophotometry, Ultraviolet


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