78 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



canaliculi, into which extend the slender cell proc* 

 esses. Through these canaliculi the imprisoned 

 cells receive their nourishment and give up their 

 waste products. 



Haversian System. This consists of a Haversian 



Haversian canal. 



Fig. 46. Haversian system with only one lacuna sketched. 



canal, containing an artery, vein, and nerve, bone 

 lamallae concentrically arranged around the canal, and 

 from two to six rows of concentrically arranged cells 

 with their lacunae and canaliculi. The canals average 

 0.05 mm. (5-^ inch) in diameter. 

 The canals, as a rule, run parallel 

 with the shaft of the bone, but com- 

 municate freely with each other. 

 The blood penetrates as far as the 

 Haversian canals but the lymph 

 reaches each bone cell through the 

 finer canaliculi. The nerve termi- 

 nates in the wall of the blood-ves- 

 sels and has no connection with the bone cells. 

 Haversian systems occupy a central zone in a bony 

 shaft. External and internal to this zone compact 

 lamellae are present, arranged parallel to the surface. 



Fig. 47. Bone 

 cell or corpuscle. 

 The cell occupies a 

 lacuna. 



