Each central canal contains a blood vessel, so every bone
cell is fairly close to a nutrient supply. In addition, the bone
cells have many cytoplasmic processes that extend outward
and pass through minute tubes in the extracellular matrix
Gap junctions attach these cellular processes
In a bone, the osteocytes and layers of extracellular
matrix, concentrically clustered around a central canal, form
a cylinder-shaped unit called an
or a Haversian sys-
tem. Many of these units cemented together form the sub-
stance of bone (see chapter 7, p. 195).
Fibrocartilage contains many large collagenous f
bers in its extracellular matrix (400×).
Cell process in
Bone tissue. (
) Bone matrix is deposited in
concentric layers around central canals. (
) Micrograph o±
bone tissue (200×). (
cially colored scanning electron
micrograph o± an osteocyte within a lacuna (6,000×).