Which connective tissue protein fibers form a meshlike framework that provides structural support for many organs?

Reticular Fibers

Explanation:

These fibers are made up of special protein known as reticulin that is composed up of collagen framework of type 3. These fibers play a role of support in bone marrow, other organs of lymphatic system as well as the liver itself. These can be visualized when a liver is cut apart. The elastic threads are reticular fibers.