Fig. 10.

Multivesicular bodies (MVB) originate from endosomes. They fill a large portion of the cytoplasm of gland cells. In TEM pictures, the degradation of their content becomes visible: vesicles are still present (a), but gradually disappear (b). They feed on the tubulo-vesicular endosomes (g) and engulf also other organelles such as mitochondria (f). Absorption of FITC-BSA shows the content of endosomes of various sizes and MVBs with degrading substance (b, c). Comparison of such late endosomes in bright-field suggests that these compartments are different from the original cell sap vacuole (V) (b, d). Staining with FM4-64 shows their membranes in the fluorescence microscope (h)