338 



HISTOLOGY OF THE MORBID PROCESSES. 



4. Bone. When a piece of bone dies fresh bone is produced 

 through a rejuvenescence of the formative activities of the periosteum 

 (or endosteum). While this new formation of bone is in progress 

 the dead bone is removed by phagocytes, which are usually multi- 



FIG. 303. 



S6SS = 



Phase in the regeneration of a tendon ; guinea-pig. (Enderlen.) Seventy days after sec- 

 tion. The tendon is still rather highly cellular, but its structure is, in the main, fully 

 restored. At the top of the figure is the cross-section of a blood-vessel. 



nucleated, and have received the name " osteoclasts" (bone-breakers), 

 in contradistinction to the bone-forming cells of the periosteum, 

 which are known as " osteoblasts " (bone-builders) (Fig. 304). 



Ik 







Regeneration of bone. (Earth.) nk, fragments of necrotic bone; rz, osteoclasts ; o, osteo- 

 blasts ; Ik, bone of new formation : g, bloodvessels ; nk', lamina of dead bone, (sp, acci- 

 dental crack in the section.) 



5. Cartilage. This tissue is capable of only a limited and imper- 

 fect regeneration. Defects in cartilage are usually made good by 



