AAT Bioquest

What are the types of lysosomes?

Posted October 14, 2022


There are four types of lysosomes: primary lysosomes, secondary lysosomes, residual lysosomes, and auto-lysosomes.

Primary Lysosomes:

Primary lysosomes are homogenous, membrane-bound organelles containing over 50 acid hydrolase enzymes. These are newly formed vesicles from the Golgi apparatus. They are small in size, and their hydrolytic enzymes come in the form of granules.

Secondary lysosomes: 

Secondary lysosomes are vesicles created from the fusion of primary lysosomes to endosomes. Digestion then occurs and the digested food is exported into the cytoplasm. The secondary lysosomes are left with the undigested food.

Residual lysosomes:

These are lysosomes in which indigestible food has been left. Residual lysosomes move outward and fuse with the plasma membrane to transport debris into the extracellular environment by exocytosis.  


These are created by the fusion of several primary lysosomes to remove weakened, old intracellular organelles. The cell debris is digested in a process known as autophagy or auto-digestion. The digested substances are then ready to be newly synthesized by the cell. This works essentially as a recycling process, and auto-lysosomes also nourish the cell during starvation.        

Additional resources

Lysosomal Biology and Function: Modern View of Cellular Debris Bin

CytoFix™ Red Lysosomal Stain