Lysosomes (Fig. 2-24) and peroxisomes (Fig. 2-27) are somewhat similar in origin and appearance, but have different functions.

• In most cells lysosomes are also more numerous.
• Study the role of primary and secondary lysosomes in intracellular digestion following endocytosis (Figs. 2-25 and 2-26).
• “Residual bodies” consist of relatively dark material called lipofuscin granules containing indigestible substances in the remains of lysosomes which may persist in cells.
• This material is sometimes visible by LM in routinely stained cells, such as the neurons on slide 135 and liver cells on slide 141.

Compare lysosomes and peroxisomes in terms of their size, contents, and function.

Mitochondria