Fig. 2.

Examples of the structure of the blood-gas barrier. A: from the African lungfish (Protopterus aethiopicus). e, Erythrocyte; p, plasma; en, endothelium; bl, basal lamina; a, alveolus; ep, epithelium; in, interstitium. [Modified from Maina et al. (20).] B: from the tree frog (Chiromantis petersi). [Modified from Maina (17).] C: from the Black Mamba snake (Dendroaspis polylepis). [Modified from Maina (18).] D: from the rat (Rattus rattus). LRE, lamina rara externa; LD, lamina densa; LRI, lamina rara interna. [Modified from Vaccaro and Brody (32).] E: from the chicken (Gallus gallus). r, Red blood cell; c, capillary a, alveolus. [Modified from Maina (18).]