Christian de Duve first observed these organelles in animal cells in 1949, by cell fractionation studies and Novikoff (1960) suggested that they are derived from pinocytic vesicles.
These are single membrane bound small vesicular structures of 0.2 – 0.5 mm in diameter or larger, rich in hydrolyzing enzymes (acid hydrolases) and you can find lysosomes pictures below.
One important property of lysosomes is their stability in the living cell. The enzymes are enclosed by a membrane and are not readily available to the substrate. This socalled latency of the lysosomal enzymes is due to the presence of the membrane.
The membrane is resistant to the enzymes that it encloses, and the entire process of digestion is carried out within the lysosome. In this way, it protects the rest of the cell from the destructive effect of the enzymes, and its stability is of fundamental importance to the normal function of the cell. Below is the description of a lysosome.
Ultrastrucuture of Lysosomes
Each lysosome is a small vesicle surrounded by a single membrane and contains about 50 strong hydrolytic enzymes (acid hydrolases), which are capable of digesting or breaking down all powerful biological substances.
Hydrolytic enzymes of lysosomes act at an acidic pH.