1034 HUMAN ANATOMY. 



The nerve-cells of the substantia gelatinosa Rolandi, also known as Gierke 's cells, include 

 innumerable small stellate, less frequently fusiform or pear-shaped elements that measure only 

 from .oo6-.o2o mm., although exceptionally of larger size. Their numerous short dendrites are 

 irregularly disposed and branched. The axones, which always arise from the dorsal pole of the 

 cell, are continued partly to the white matter of the posterior column, within which they divide 

 into ascending and descending limbs, and partly to the gray matter itself, within which they run 

 as longitudinal fibres. Under the name of the marginal cells are described the much larger 

 (.035-.055 mm. ) nerve-cells which occupy the border of the substantia gelatinosa. They are 

 spindle-shaped or pyramidal in form, their long axes lying parallel or the apices directed towards 

 the Rolandic substance respectively, and constitute a one-celled layer enclosing the substantia 

 gelatinosa, into which many of their tangentially coursing dendrites penetrate. Their axones 



lirough the substantia gelatinosa and probably continue for the most part within the lateral 

 column, although some enter the posterior column ( Cajal, Kolliker). 



The inner cells of the posterior horn are intermingled with numerous nervous elements of 

 small size irregularly distributed within the head of the dorsal cornu. The inner cells proper 

 are triangular or spindle-shaped in form and, on an average, measure about .050 mm.; they 

 are, therefore, larger than the ordinary cells of the Rolandic substance. The dendrites arise 



IMG. 889. 



White matter of '.sl^^^^^B^ - ' ^ 



posterior column -rvrfflMRIBEM&fc. 



, 



Cells of Clarke's column 



Suhstaiitii gelatinosa cetiiralis ^^ 



/ 

 Central camil 



Part of cross-section of cord, showing cells of Clarke's column in base of posterior horn. X no. 



from the angles or ends of the cells and diverge in all directions. The axones pass, either 

 directly nr in curves, mostly into the lateral column of the same side; some, however, have 

 been followed into the posterior or anterior columns of the same side (Kolliker), and, rarely, into 

 tin- opposite anterior column (Cajal). Exceptionally type II cells those in which the axone i-, 

 not prolonged as the axis-cylinder of a nerve-fibre, but soon breaks up into an elaborate end 

 arbori/ation confined to the gray matter are found within the gray matter of the posterior horn. 

 Their number is, however, much less than often assumed (Xiehen). 



The nervous character of most of the cells seen within the substantia gelatinosa Rolandi lias 

 l>'-en established only since the introduction of the C.olgi methods of silver-impregnation. 

 I'r.-vloiislv. these elements u !<] .is glia celK, ;m exceptionally large amount of 



m-nroglia in general being attributed to the Rolandic substance. It is now 'admitted that 

 instead of such being the case, this region of the gray matter is relatively poor in neiirogliar 

 elements and numerically rich in nerve-o-lls. 



The nerve-cells of the pars intermedia of the -ia\- matter, which connects 

 the dorsal and ventral horns and lies opposite the grav commissure, may be broadly 

 divided into two classes, the lateral and the middle cells, that occupy respectively the 



outer border and the more central area of this part of the gray matter of the cord 



