THICKNESS OF THE AIR-BLOOD BARRIERS IN VERTEBRATE LUNGS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 131  (SEP) , 299-307
Abstract
Thickness of the lung air-blood barriers of mammals (8 spp.), reptiles (10 spp.) and amphibians (10 spp.) was estimated using EM stereological methods. There was considerable variation in the measurements, the thickest barrier being that of the crested newt (2.81 .mu.m) and the thinnest that of the mouse (1.27 .mu.m). The arithmetic mean thickness of the barriers was related to body weight in mammals but not in reptiles and amphibians. There were no significant differences between the minimum thickness of the barriers nor in the volume proportions of their constituent layers in the 3 animal orders. The ratio of the arithmetic mean thickness to the harmonic mean thickness of the barriers was highest in mammals. Apparently the process of optimization of lung architecture for gas exchange is most marked in mammals.