MAKROW 



53 



blood-corpuscles (h&matoblasts). Lastly the marrow contains a certain 

 number of very large cells with multiple nuclei, the myeloplaxes (fig. 

 63, a, b, c, d). These are especially numerous wherever bone is 

 becoming absorbed. The marrow is very vascular, the capillaries and 

 veins being large and thin-walled ; indeed, according to some authorities, 



m n o p 



o 



9 



10 



FIG. 63. CELLS OF THE RED MARROW OF THE GUINEA-PIG. (Highly magnified.) 



a, a large cell, the nucleus of which appears to be partly divided into three by constrictions ; 

 6, a cell the enlarged nucleus of which shows an appearance of being constricted into a 

 number of smaller nuclei ; c, a so-called giant-cell or myeloplaxe with many nuclei; d, a 

 smaller myeloplaxe with three nuclei ; e-i, proper cells of the marrow ; j-t, various forms 

 of coloured nucleated cells, some in process of division. 



the walls of the capillaries are imperfect, so that there is an open com- 

 munication between them and the interstices of the tissue, and in this 

 way it is supposed that the coloured blood-disks, which are believed to 

 be produced from the coloured nucleated cells of the marrow, may get 

 into the circulation. 



