The blood supply to bone tissue is essentially centrifugal.
The blood that nourishes bone tissue moves from the marrow cavity into and through the bone tissue and out via  periosteal veins; thus, its flow is in a centrifugal direction. With respect to nourishment of the bone tissue itself, Volkmann’s canals provide the major route of entry for vessels to pass through the compact bone. The smaller blood vessels enter the Haversian canals, which contain a single arteriole and a venule or a single capillary. A lesser blood supply to the outermost portions of the compact bone is provided by the branches of periosteal arteries (see Fig. 8.4). Bone tissue lacks lymphatic vessels; lymphatic drainage occurs only from the periosteum.
Bone tissue initially formed in the skeleton of a developing fetus is called immature bone. It differs from mature bone in several respects (Fig. 8.5):  Immature bone does not display an organized lamellated appearance. On the basis of its collagen fiber arrangement, such bone is designated nonlamellar. Nonlamellar bone is also referred to as bundle bone or woven bone because of the interlacing arrangement of the collagen fibers.
osteoclast resorption canal osteocyte osteocyte interstitial lamellae MATURE BONE IMMATURE BONE osteon concentric lamella a b FIGURE 8.5 • Diagram of immature and mature bone. Immature bone does not display an organized lamellar appearance because of the interlacing arrangement of the collagen fibers. The cells tend to be randomly arranged, whereas the cells in mature bone are organized in a circular fashion that reflects the lamellar structure of the Haversian system. Resorption canals in mature bone have their long axes in the same direction as the Haversian canals.
than does mature bone.  The cells in immature bone tend to be randomly arranged, whereas cells in mature bone are usually arranged with their long axes in the same direction as the lamellae.  The matrix of immature bone has more ground substance than does the matrix of mature bone. The matrix in im mature bone stains more intensely with hematoxylin, whereas the matrix of mature bone stains more intensely with eosin.
Although not evident in typical histologic sections (Fig. 8.6), immature bone is not heavily mineralized when it is initially formed, whereas mature bone undergoes prolonged secondary mineralization. The secondary mineralization of mature bone is evident in microradiographs of ground sections that show younger Haversian systems to be less mineralized than older Haversian systems (see Fig. 8.22).
Immature bone forms more rapidly than mature bone. Although mature bone is clearly the major bone type in the adult and immature bone is the major bone type in the developing fetus, areas of immature bone are present in adults, especially where bone is being remodeled. Areas of immature bone are common in the alveolar sockets of the adult oral cavity and where tendons insert into bones. It is this immature bone in the alveolar sockets that makes it possible to make orthodontic corrections even in adults.
As noted previously, five designated cell types are associated with bone tissue: osteoprogenitor cells, osteoblasts, osteocytes, bone-lining cells, and osteoclasts. With the exception of the osteoclast, each of these cells may be regarded as a bone). In contrast, the osteoclast originates from a different differentiated form of the same basic cell type (Fig. 8.7). Each cell line and is responsible for bone resorption, an activity as-undergoes transformation from a less mature form to a more sociated with bone remodeling. mature form in relation to functional activity (growth of