Figure 2.

At the ultrastructural level, Young cell: (A) There are a number of autolysosomes (black arrowheads) at early stages of degradation. Different types of material are seen inside. There is already some degradation going on as the multi-membranous structure (called onion-like) is seen, which appears often when degradation is very active. An autophagosome with density similar to the surrounding cytosol and a double membrane (upper white arrowheads) and one with mitochondria inside (lower white arrowheads) are seen, (B) This is also an area of high autophagic activity where autophagosome (white arrowheads) and autolysosomes (black arrowheads) at different stages of degradation area seen. There is also a fresh, very long mitochondria fused to the mitochondrial network (red arrowheads). Old cell: (C) There is an autophagosome (white arrowheads) with a mitochondria inside. (D) A number of autolysosomes (black arrowheads) are seen. (E) A residual body (R), a lysosome containing indigestible materials is seen.