I034 



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 .006-.020 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 

 pass through 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 



Fig. 8S9. 



White matter of 



posterior column 



Cells of Clarke's column 



Substantia gelatinosa centralis 



Central canal 

 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 or 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 

 the opposite anterior column (Cajal). Exceptionally type II cells — those in which the axone is 

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

 arborization confined to the gray matter — are found within the gray matter of the posterior horn. 

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



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

 been established only since the introduction of the Golgi methods of silver-impregnation. 

 Previously, these elements were regarded as glia cells, an exceptionally large amount of 

 neuroglia 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 neurogliar 

 elements and numerically rich in nerve-cells. 



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

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

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

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



