Figure 2.

Structural aspects of the endosome-lysosome system involved in intracellular digestion. a Schematic diagram of phagocyte with its intracellular membrane bound compartments. Left side of diagram shows the endosomal-lysosomal pathway (thick gray hatched line) that degrades small food particles absorbed by pinocytosis. Compartments are identified by terms generally used in current textbooks and research literature. Right side of diagram depicts the phagosome-lysosome pathway followed by large food particles ingested by phagocytosis. Electron micrographs (b-b’””, c’-c”, d, e) illustrate shape and texture of compartments shown in a. b Clathrin-coated endocytic pit. b’ Non-clathrin-coated endocytic pit. b” Early Endosome. b’” Late Endosome/Multivesicular body. b”” Lysosome. b’”” Endolysosome. c Phagosome containing bacteria. c’ Two phagolysosomes; the one at bottom containg partially digested bacteria. d Lipid bodies and glycogen particles. e Residual bodies. b: from (Mayor and Pagano 2007) with permission; b-b’””: from (Huotari and Helenius 2011) with permission; c from (Hard 1972) with permission; d, e: from (Del Conte 1979) with permission.

Scale bars: 100nm (b-d); 500nm (e).