74 



CONNECTIVE TISSUE CARTILAGE BONE 



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bone, becomes ossified later in life. It represents the line of growth, and 

 is the last portion of fetal cartilage to be transformed into adult bony 

 tissue. 



Periosteum. All those portions of the bone which are not covered by 

 an articular cartilage are supplied with a membranous coat of fibrous 

 tissue, the periosteum. The outermost layer of this membrane consists 



of interlacing bundles of dense fibrous 

 tissue in which are the larger blood- 

 vessels, whose branches are distributed 

 to the underlying bone. The inner 

 portion of this layer forms a firm 

 fibre-elastic stratum, which in older 

 individuals is closely attached to the 

 surface of the bone. The periosteum 

 of developing and growing bone, how- 

 ever, contains a third or innermost 

 areolar layer, in which are small 

 blood-vessels, fine connective tissue 

 fibrils, and numerous small osteogenic 

 cells, the osteoblasts. After growth 

 of the bone has ceased, the deepest 

 layer of the periosteum contains few 

 small blood-vessels and only occa- 

 sional osteoblasts. These cells, how- 

 ever, are present in sufficient numbers 

 to accomplish the regeneration of the 

 bone after destruction of its osseous 

 tissue. 



The medullary surface of the bone 

 is likewise supplied with an osteo- 

 genic membrane of fibrocellular tis- 

 sue, similar to the innermost layer of 



the periosteum; it is known asi the periosteum interiium, endosteum, or 

 membrana medullaris. 



Compact Bone. Compact bone, such as that composing the shafts 

 of the long bones, consists of concentric lamellce of calcified fibrous tissue 

 which constitute the Haversian systems, together with groups of parallel 

 laminae,, which are interposed between adjacent Haversian systerns and 

 are known as the interstitial or ground lameUce. Many of the interstitial 

 lamella? are the remains of Harversian systems which have been partially 



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FIG. 87. LONGITUDINAL SECTION OF 

 GROUND BONE FROM THE SHAFT OF 

 THE HUMAN FEMUR. 



a, Haversian canals; 6, lacunae; c, 

 canaliculi. X 100. (After Kolliker.) 



