Lysosomes. Coloured transmission electron micrograph (TEM) of some lysosomes in a mammalian kidney cell. Lysosomes (blue) are fluid-filled membranes, or vesicles, containing a concentrated mix of digestive enzymes. Here secondary lysosomes are digesting redundant cell organelles or damaged molecules (green/purple) within the cell. A primary lysosome becomes a secondary lysosome once its membrane has fused with its target. Digestion products diffuse through the lysosomal membrane into the cytoplasm (pink). Primary lysosomes are produced by the golgi apparatus. Magnification: x15,000 at 35mm size.