ORIGIN AND FATE OF OSTEOCLASTS 319 



Fate. Concerning the ultimate fate of the osteoclast, there 

 is also no general agreement. 



These giant-cells were viewed by Bredichin ('67) as transi- 

 tional stages in the transformation of bone tissue into marrow 

 and granulation tissue. 



Wegner ('72), observing some polykaryocytes with cavernous 

 recesses, was led to speculate as to whether new blood-vessels 

 might arise from such (compare p. 327). He also believed in 

 their resolution into connective tissue, or, perhaps, marrow 

 cells. 



Kolliker ('73) noted that when bone deposition again succeeds 

 a period of resorption, the osteoclasts disappear from the resorp- 

 tion area' and are superseded by osteoblasts. Furthermore, 

 where resorptive and formative areas join he found intermediate 

 types. The conclusion is drawn that, in such situations at 

 least, the osteoclasts fragment and return to osteoblasts. 

 Kolliker, nevertheless, emphasizes the absence of direct proof 

 and admits (p. 27) that: "Die letzten Schicksale der Osto- 

 klasten sind noch in grosses Dunkel gehlilt." Allowance is also 

 made for the degeneration of some of the giant-cells and for the 

 possibility of a transformation of others into connective-tissue 

 and marrow cells, as Wegner ('72) contended. 



Gegenbaur 5 and Bassini ('72) agreed with these views of 

 Kolliker. Pommer ('81) likewise held that osteoclasts not 

 only revert to osteoblasts, but also to cells of a different char- 

 acter and to intercellular material, whereas at the suppression 

 of sufficient nutriment they degenerate. 



The removal of the stimulus to absorption was believed by 

 Morrison ('73) to lead to the disappearance of the osteoclasts 

 by 'molecular degeneration.' 



Lowe (79) presented a curious and incredible account of the 

 encapsulation of osteoclasts, the fragmentation of their nuclei 

 and cytoplasm into discrete cells, the rupture of the capsular 

 wall, and the dispersal of the individual elements into the marrow. 

 He remarks on the similarity between these stages and those 

 of encystment and spore formation in protozoa. 



5 Cited by A. Bidder ('06). 



