What is the structure of lysosomes?

Lysosomes are spherical shaped, membrane-bound organelles contained by an outer lysosomal membrane. Their spheres are composed of a lipid bilayer that encompasses fluid of different hydrolytic enzymes. The lipid bilayer is composed of typical phospholipids, with a hydrophilic head, a glycerol molecule, and a hydrophobic tail. Lysosomes are very small in size, typically ranging from 0.1-0.5 micrometers, and reaching up to 1.2 micrometers maximum. The purpose of the outer membrane is to protect the rest of the cell from the digestive enzymes which stay inside the membrane.