Autolysis

Normally, the lysosomal membrane is impermeable to its own enzymes. This prevents digestion of the cellular contents. 

However, sometimes autolysis, or self destruction, by lysosomes occurs. 

For example, during human embryological development, the fingers and toes are webbed. The normal development of individual fingers and toes requires the selective removal of the cells of the web between the digits.

This involves autolysis, in which lysosomal enzymes digest the tissue between the digits. It is actually a programmed destruction of cells.