TISSUES. 8l 



The periosteum is anchored to the compact bone by 

 means of bundles of fibers (Sharpey's fibers) that 

 pass concentrically or parallel to the Haversian 

 systems. 



Blood Supply. The compact bone is supplied 

 with blood from the periosteum. Larger blood- 

 vessels, called perforating vessels, pass directly 

 through the bony shaft and supply the marrow. 

 In removing bone, as a rib, the periosteum is not 

 taken away, and because of the latter 's vascularity 

 and osteogenetic layer, the removed part regenerates. 

 On the other hand, infected marrow and diseased 

 bone may be removed from the inner surface until a 

 mere shell remains of the once solid shaft. If all 

 the infection is removed a regeneration follows. 



Development of Bone. The development of bone 

 is either intramembranous or endochondral. In the 

 latter a cartilage stage intervenes, otherwise the 

 history in each case is the same. A synopsis of 

 endochondral development is as follows: 



1 . A solid shaft of hyaline cartilage, non-vascular 

 and without any marrow cavity. 



2. In the center of this shaft the cartilage cells 

 enlarge, their lacunae enlarge and coalesce, particu- 

 larly along lines extending toward the ends of the 

 bone. The rosette produced by this excavation is 

 called the primary areola of Sharpey. 



3. Lime salts are deposited in the thin walls of 

 these spaces, making calcified cartilage. 



4. Osteogenetic cells and blood-vessels from the 

 periosteum enter the cartilage spaces. The carti- 

 lage cells disappear with this invasion and the ex- 



