FIG. 94. 





. 



78 NORMAL HISTOLOGY. 



the nuclei of the endothelioid plates lying within the interlamellar 

 lymphatic spaces. The endoneurium is directly continuous with the 

 perineurium, of which it is the intrafunicular extension. 



Where a nerve-trunk Comprises several funiculi, these are held 

 together and envelope^ by a loose general connective tissue the 

 / epineurium which supports the blood- 

 vessels and lymphatics, and often contains 

 masses of adipose tissue ; the external layer 

 of the epineurium is usually somewhat 

 condensed. 



When the funiculus divides, the new 

 ^bundles receive a prolongation of the peri- 

 -jneurium, the investment becoming thinner 

 'with each successive division. On nearing 

 their final destination, the funiculi break up 

 into small groups or single fibres, which are 

 covered by an attenuated extension of the 

 formerly robust perineurium ; this invest- 

 ment constitutes the sheath of Henle, and 

 consists of a delicate fibrous envelope lined 

 with endothelioid plates ; in some cases these 

 latter alone represent the entire sheath. 



The larger blood-vessels enclosed within 



the epineurium give off branches, which surround the funiculi and 

 break up into capillaries passing within the endoneurium among the 

 fibres. 



The lymphatics are represented by irregular clefts within the 

 endoneurium, which are connected with the interlamellar spaces of 

 the perineurium ; from these the lymph is taken up and carried off 

 by the more definite lymphatic channels running within the epineu- 

 rium. 



The nerves of the larger trunks the nervi nervorum are dis- 

 tributed within the epineurium, and are said to terminate, in many 

 cases, in special bodies which resemble in general type the spherical 

 end-bulbs of Krause. 



THE SUPPORTING TISSUES OF THE NERVE-CENTRES. 



The essential constituents of the nervous system, the cells and 

 fibres, when associated in large masses, as in the cerebro-spinal tract, 

 are held in place and supported by two varieties of sustentacular 

 tissue. On examining suitably prepared sections of these organs, 

 the cells and fibres appear everywhere to be embedded within a finely 

 reticulated ground-substance, whose composition is especially 

 complex in the gray matter. The basis of this reticulum is the 



A single funiculus more highly 

 magnified ; the apparent small 

 nucleated cells are sections of the 

 nerve-fibres and their axis-cylin- 

 ders : a, axis-cylinder ; <w, med- 

 ullary substance ; n, neurilemma ; 

 e, endoneurium ; /, perineurium ; 

 b, connective-tissue cells of same. 



