484: MOVEMENTS. 



all ages, but are more abundant in proportion as the amor- 

 phous matter and fat-cells are deficient. The nuclei are 

 spherical, with borders sometimes irregular, generally with- 

 out nucleoli, finely granular, and from ^^Q-Q to -g-gVo of an 

 inch in diameter. They are insoluble in acetic acid. 1 The 

 cells are less numerous than the free nuclei. They are 

 spherical or slightly polyhedric, contain a few pale granu- 

 lations, are rendered pale, but are not dissolved by acetic 

 acid, and measure about 17 1 00 of an inch in diameter. 2 



Myelopldxes. These are irregular, nucleated patches, 

 also described by Robin, more abundant in the spongy por- 

 tions of the bones than in the medullary canals, and are 

 applied to the internal surfaces of the bones. They are ex- 

 ceedingly irregular in size and form (measuring from 12 1 00 

 to -^Q of an inch in diameter), are finely granular, and pre- 

 sent from two to twenty or thirty nuclei. The nuclei are 

 clear, ovoid, generally with a nucleolus, and are from %^ Q 

 to innnr of an incn lon g> by -g^ to ^^ of an inch broad. 

 The myeloplaxes are rendered pale by acetic acid, and the 

 nuclei are then brought out more distinctly. 8 



In addition to the anatomical elements just described, 

 the marrow contains a few very delicate bundles of connec- 

 tive tissue, most of which accompany the blood-vessels. In 

 the foetus the adipose vesicles are few or may be absent ; 

 but in the adult they are quite numerous, and in some bones 

 seem to constitute the whole mass of the marrow. They do 

 not differ materially from the fat-cells in other situations. 

 Holding these different structures together, is a variable 

 quantity of semitransparent, amorphous, or slightly granu- 

 lar matter. 



The nutrient artery of the bones sends branches to the 

 marrow, generally two in number for the long bones, which 

 are distributed between the various anatomical elements, and 



1 LITTRE ET ROBIN, Dictionnaire demedecinc, Paris, 1865, Article, Medullocelle. 



2 POUCHET, Precis d'histologie humaine, Paris, 1864, p. 106. 



3 LITTRE ET ROBIN, Dictionnaire de medecine, Paris, 1865, Article, Myeloplaxe. 



