592 DR JAMES W. DAWSON ON 



(3) Histological Characteristics in Special Situations. 



1. White Matter. 



This has already been fully considered, as the areas described in the previous 

 sections were all in the white matter of the brain and cord. 



2. Grey Matter. 



(a) Central Grey Matter. 



Where the sclerotic process affects the grey matter of the spinal cord and the 

 corresponding nuclei of grey matter in the medulla oblongata and pons, we find that 

 the changes in their evolution correspond very closely to those in white matter in 

 which the nerve fibres form a reticulum. 



The myelin network quickly disappears, and in its place we get a thickened glia 

 reticulum with large meshes and numerous hypertrophied glia cells. These spider 

 cells, with relatively numerous processes, varying in length and thickness, give rise 

 to a fibril formation analogous to that already described — the resulting meshwork 

 being very close. The formation of fat granule cells is always much less marked 

 than in the white matter ; their size is smaller and the structure of their granules 

 more delicate. This corresponds to the lessened quantity of myelinated fibres in 

 the grey matter, but the process of their formation, the absorption of the degenerated 

 myelin, their presence in the glia meshes, and their gradual removal in the lymphatic 

 spaces of the vessels is quite similar to that elsewhere. The vessels passing from the 

 borders of the grey matter into the white matter form often radial lines, the 

 commissural vessels and the vessels in the anterior median fissure also take their 

 share in this removal of degenerated products. 



The ganglion cells in this reticulum seem to remain long preserved (fig. 417), and 

 in this investigation changes, which could be distinctly traced to the sclerotic 

 process, were found only when an advanced degree of sclerosis had been reached 

 (fig. 419). The cells undoubtedly remain long with their normal form and minute 

 structure preserved. The processes first lose their structure and, as the sclerosis 

 becomes denser, the cell bodies share in this change. In the later stages they show 

 all the possible changes which are traceable to a slow simple atrophy from loss of 

 function (fig. 409) or from compression on the part of the developing cells and fibrils 

 of the interstitial tissue (fig. 419). Diffusely extensive changes in the ganglion cells 

 (fig. 411) should probably be referred to somatic general disturbances which accom- 

 pany the disease, e.g. the fever, anaemia, exhaustion, or direct septic absorption from 

 bed-sores or a pyelitis, and can thus not be looked upon as specific to disseminated 

 sclerosis. In numerous affected segments which microscopically showed complete 

 demyelination, many of the ganglion cells showed no changes — completely normal 

 cells being found alongside those with marked chromatolysis or atrophy. 



