The (1) is the shapeless background against which collagen fibers are seen through the microscope. Molecules
in ground substance include (2), a long, unbranched
polysaccharide that is very slippery, and (3), which are
formed from proteins and polysaccharides. Proteoglycan
(4) are composed of 80-100 polysaccharides, called
(5), each attached at one end to a common protein core.
If the protein cores of proteoglycan monomers attach to
hyaluronic acid, proteoglycan O are formed.
Proteoglycans trap large quantities of (7), which allows
them to return to their original shape when compressed or
deformed. Several adhesive molecules are found in ground
substance, including (8) in cartilage, 12 in bone, and
(10) in fibrous connective tissue.