1. In mammalian cells, __autophagosomes are thought to form de novo from contact sites between the ER and mitochondrial outer membrane.__
2. __Once formed, the outer membrane of the autophagosome fuses with a lysosome to make a structure called autolysosome.__
3. __After the digestive process of the autolysosome, the organelle is called a residual body.__
4. __Depending on the cell type, the residual body contents may be eliminated from the cell through exocytosis. Otherwise, they could be retained within the cytoplasm indefinitely as a lipofuscin granule.__