Figure 5
Ultrastructure of pulmonary capillaries in P. nigromaculatus and B. gargarizans by TEM. TEM observation of the pulmonary capillaries in P. nigromaculatus and B. gargarizans. TEM observations of the structures of the capillaries in B. gargarizans (A–L) and P. nigromaculatus (M–R). The capillary is located in a protruding thick fold (A,B) and under the basement membrane (*). The capillary (Ca) might swell (A,B) or shrink (C,D). The red blood cells (RBCs) (E,F) do not fill the capillaries. Endoplasmic reticulum and microvilli (G,H, white thick arrow). The thin fold does not contain capillaries (I,J). Dense microvilli in thin folds (K,L). The capillary is located under a sheet with sparse microvilli and a thin basement membrane (M,N). Sharp corner (white thick arrow) at the edge of the sheet (N). The two sheets interconnect and form a slight dent (O,P, black thick arrow). The capillaries contain one (O,P) or two layers (Q,R) of RBCs that fill the capillaries (Q,R). B, D, F, H, J, L, N, P, and R show enlarged images of the boxes in A, C, E, G, I, K, M, O, and Q, respectively. The white thin arrow shows melanosomes, and the black thin arrow indicates microvilli. Scale bar, A, E, G, K, M: 1 μm; C, I, O, Q: 2 μm; B, F, H, L, N: 0.35 μm; D, J, P, R: 0.7 μm. Density of microvilli (S), thickness of the blood-air barriers (T), and area of capillaries (U) in the inflated lungs of both B. gargarizans and P. nigromaculatus. The error bars indicate the SEMs, t test, two-tailed, *p < 0.05, **p < 0.01, ***p < 0.001.
