318 LESLIE B. AREY 



Ranvier ('89), Renault ('93), and Duval ('97) trace the origin 

 to lymphoid marrow cells, whereas Mallory ('11) insists that 

 osteoclasts arise unquestionably from fused, large mononuclear 

 leucocytes. 



The results of Jackson ('04), Danchakoff ('09), and Maximow 

 ('10) agree in tracing the origin of the first osteoclasts in the early 

 stages of bone development to enlarged reticular cells of bone 

 marrow. These cells possess at first but two or three nuclei 

 and the cytoplasm is basophilic. Later their cytoplasm appears 

 oxyphilic and the nuclei may become extremely numerous. 



Osteoclasts are viewed by Todd ('13) as "masses of preosseus 

 tissue artificially separated from the fully ossified bone during 

 its preparation for histological examination." 



The views of Wegner, Kaczander, Todd and Geddes, just 

 presented, are unusual, some of them seemingly even fanciful. 

 In my experience they demand no serious attention. The 

 remaining workers trace or infer an origin from osteoblasts, 

 bone cells, or marrow tissue of some sort. The relation of these 

 opinions to my own observations will be made clear in the pages 

 which follow. Briefly, I recognize all three sources of origin, 

 but the interpretation of the actual mode of genesis and growth 

 of the osteoclast, and the relative importance of each contribu- 

 tory element is novel. 



Multinuclearity . A variance of opinion exists also as to the 

 manner in which the osteoclast comes to possess its numerous 

 nuclei. 



Kolliker ('73) considered the increase in nuclei to result from 

 nuclear division. Adherents to this view include Bredichin 

 ('67), Wegner (72), Morrison ('73; by amitosis), Bohm and 

 Davidhoff 4 (by mitosis), Jackson ('04 by mitosis); and Jordan 

 ('18; by mitosis, to a limited degree). 



Morrison ('73) and Danchakoff ('09) speak of the confluence 

 of mesenchymal cells. Maximow ('10) likewise believes that 

 large osteoclasts arise at the expense of smaller ones; further- 

 more, he records having never observed nuclear division either 

 by mitosis or amitosis. 



4 Cited by A. Bidder ('06). 



