Osteocytes have numerous cell processes but they are not seen in regular routine sections stained with hematoxylin and eosin and observed with a light microscope.
The cell bodies of osteocytes occupy the small cavities of the matrix called lacunae and their extensions occupy thin tunnels that originate in the lacunae, called canaliculi (plural of canaliculus).
The end portion of the canaliculi connect with neighbor canaliculi. Therefore the osteocytes communicate with each other and form an extensive net inside the bone matrix. This net is very important for the bone metabolism, as its extracellular matrix is not permeable to the transit of gases and liquids. Nutrients, gases and many molecules are conducted inside the canaliculi.
The figure is of a small bone specimen specially prepared to demonstrate bone lacunae and canaliculi. The specimen was placed in a solution of the dye Thionine that difused into the spaces of the osteocytes and of their processes.
What is seen in the image is the dye inside the lacunae inhabited by osteocyte cell bodies (larger arrows) and the canaliculi occupied by extensions of osteocytes (smaller arrows).
Section of a bone specimen that had been placed in thionine solution. Medium magnification.