2I 4 



PRACTICAL HISTOLOGY. 



[XVIII. 



sule (fig. 197, c) surrounding the ganglion; nerve-fibres (a) enter 

 the ganglion at one end and leave it at the other. They run in 

 groups, chiefly through the central part of the ganglion, so 

 that they are cut in different planes. 



(6.) Numerous spherical cells (tig. 197, b) lying singly or in 

 groups between the nerve-fibres, but chiefly towards the surface. 



(c.) (H) Select a single ganglion-cell; note its spherical shape, 



FIG. 197. L.S. Spinal Ganglion, a. Nerve-fibres; b. Nerve-cells ; 

 c. Capsule of the ganglion. 



its granular contents, and single, large, distinct, excentrically-placed 



nucleus, often with one or more distinct nucleoli (fig. 198). The 



nucleus has a well-defined nuclear membrane. 



(d.) Around each cell is a capsule, which is lined by a single 



layer of flattened cells, but only the nuclei of these cells are seen. 

 The cell-substance is frequently somewhat re- 

 tracted from the capsule, so that a space may 

 intervene between the two. 



In a T.S. of such a ganglion, notice the capsule 

 of the ganglion sending in coarse septa, the nerve- 

 cells near the circumference, and the nerve-fibres 

 chiefly in the centre. 



2. Isolated Cells of a Spinal Ganglion 

 (Mammal) (H). Into a dorsal ganglion of a 

 young rabbit make an interstitial injection of 

 osmic acid (2 per cent.). Tease a small piece in 

 picro-carmine and mount the preparation in 



, . ,. n j i i i 



glycerine. bometimes a cell with its single 

 process may be found. The cells are unipolar. It is more difficult 

 to find the connection of the issuing axis-cylinder with a nerve- 

 fibre, forming what Ranvier has described as T-shaped nerve-fibres, 

 but with care such processes can be found. 



plasm shrunk from 



the Capsule, x 200. 



