Fig. 6

A–C Electron photomicrograph of SC-PG showing: A Thin blood-air barrier (double arrow), patent alveoli (PA) and intact intercellular junctions (J). Bc; blood capillary. P1; type I pneumocyte. B Type I pneumocyte showing large euchromatic nucleus (N) and few profiles of rough endoplasmic reticulum cisternae (r). C Large bulging type II pneumocyte with characteristic microvilli (MV), lamellar body (LB) and mitochondria (m). P1; type I pneumocyte. Scale bar A–C 2 µm. D–H Electron photomicrographs of SC-TG showing: D Thin interalveolar septum with few collagen fibrils (C). PA; patent alveolus, Bc; blood capillary. E Type I pneumocyte showing slightly bulging euchromatic nucleus (N). Thin BAB can be seen (double arrow). Bc; blood capillary. C; collagen. F Type I pneumocyte showing euchromatic flattened nucleus (N) and dilated profiles of rough endoplasmic reticulum cisternae (r). G Type II pneumocyte showing many lamellar bodies (LB) and a microvillus border (MV). Arrow: mildly dilated perinuclear cisterna. C; collagen, N; nucleus. H Two interstitial type II pneumocytes (P2) showing lamellar bodies (LB). A small nucleus is seen in one of them (N). P1; type I pneumocyte. Scale bar D 5 µm, E–H 2 µm. I–L Electron photomicrographs of Unt-G showing: I Thick interalveolar septum with many interstitial cells (IS) having irregular small nuclei, some with mildly dilated perinuclear cisterna (white arrow). A macrophage with its characteristic kidney-shaped nucleus (M1) is depicted. Another macrophage is seen in the alveolar lumen (M2) with many lysosomes (L) and pseudopodia (PD). Notice interstitial oedema (star). J Thick interalveolar septum containing interstitial cells (IS) with irregular heterochromatic nuclei. Type I pneumocyte (P1) with an irregular heterochromatic nucleus and type II pneumocyte (P2) with empty lamellar body (LB) are also seen. Notice interstitial oedema (star). K A type II pneumocyte showing dense cytoplasm (P2), an irregular dense nucleus (N) and few lamellar bodies (LB). Another type II pneumocyte (P2) shows many cytoplasmic vacuoles (V) and mildly dilated perinuclear cisterna (white arrow). A third type II pneumocyte is extruded into the alveolar lumen (black arrow). P1; Type I pneumocyte with underlying collagen (C). J; intercellular junction. L Type II pneumocyte with heterochromatic small nucleus (N) and empty lamellar bodies (LB). Bc; blood capillary, C; Collagen. Scale bar I–L 2 µm. n = 10 in all groups