1178 



HI. MAN ANATOMY. 



FIG. 1016. 



with the collaterals and similarly directed processes from other cells, take part 

 in producing the felt-work giving rise to the outer stripe of Baillarger. From 

 the deeper or basal surface of the cell arises the delicate centrally directed axone, 

 which, penetrating the intervening fourth layer, acquires a medullary coat and 

 enters the white core of the convolution as one of the component nerve-fibres. 

 The axone gives off one or more collaterals which, after a shorter or longer 

 course, establish relations with other and often remote cells. In addition to the 

 two chief processes, the peripherally directed apical dendrite and the centrally 

 coursing axones, a variable number from four to twelve of secondary lateral 



dendrites spring from the basal 

 angles of the cell. These processes 

 usually divide dichotomously, each 

 succeeding pair of branches in turn 

 splitting into twigs, until the den- 

 drite is resolved into an end-brush 

 of fibrillse which aid in producing 

 an intricate felt-work of finest 

 threads. Each pyramidal cell con- 

 tains a conspicuous spherical or 

 ellipsoidal nucleolus, within which 

 a distinct nucleus is usually distin- 

 guishable. The cytoplasm exhibits 

 a striation and, in addition to the 

 masses of tigroid substance, the 

 Nissl bodies, a mass of brownish 

 pigment granules. The larger 

 pyramidal cells are surrounded 

 by an evident pericellular lymph- 

 space. 



The layer of polymorphic 

 cells includes a large number of 

 small nerve-cells, from .008 .010 

 mm. in diameter, whose forms 

 vary greatly, irregular, spherical, 

 triangular, stellate and fusiform 

 elements being present. Small 

 pyramidal cells are also often seen 

 within this layer. In contrast to 

 dendrites of the typical pyramidal 

 cells, those of the polymorphic 

 elements, although peripherally 

 directed, do not reach the stratum 

 zonale but end before gaining the 

 outermost layer. Their axones 

 puss into the subjacent fibre- 

 layer. The radial disposition 

 of the groups of til IKS within 



Nerve cells of cerebral cortex as sern after silver im- tne deepest Stratum OI the 

 pregnation. X 90. Drawn from pivpaiaii..n made by Pro- COltical Substance limits the 

 lessor T. G. Lee. . . . .. . . ,, .. 



polymorphic cells chiefly to the 

 interfascicular areas, within which the cells consequently appear arranged in a 



sonit-wliut cnliimiiur order. 



Within the deeper layers of the cortex, therefore umoiig the polymorphic 

 and the pyramidal elements, two additional varieties of nerve-cells are encountered. 

 These are the cells of Murtinotti and the cells of Gol^i. 



The cells of Martinotti are of small si/c uiul triangular or spindle-form in 

 outline and particularly distinguished by the unusual direction of their axones. 

 These processes puss towards the surface and within the stratum xonale divide 

 into branches, which an- continued horizontally in the felt-w. n k of tangential fibres. As 



Large pyra- 

 midal cells 





Polymorphic 



Pols 



cellV 



