NERVE TISSUE 



137 



short distance after leaving the nerve cell body, and also just before 

 reaching their terminations. 



(b) N on-medidlated axones with a neurilemma — fibres of Remak 

 (Fig. 80). In these the axone is surrounded by a delicate homo- 

 geneous, nucleated sheath, the neurilemma or sheath of Schwann 

 (see p. 139). These axones are described by some writers as having 



r ^"1 



ABC 



Fig. 80. Fig. 81. 



Fig. 80. — Non-meduUated Nerve Fibres with Neurilemma, only the nuclei of which 

 can be seen. X300. 



Fig. 81. — A, Fresh nerve fibre from sciatic nerve of rabbit teased apart in normal 

 salt solution, showing broad unshrunken axone and comparatively thin medullary 

 sheath. B, Showing crenation of medullary sheath which occurs soon after placing 

 fibres in salt solution. C, Same after fixation and staining with picro-acid-fuchsin, 

 showing shrunken axone and broad medullary space. The latter usually contains 

 irregular clumps of myehn. a, Node of Ranvier; b, incisures of Schmidt; c, nucleus of 

 neurilemma. 



no true neurilemma, but merely a discontinuous covering of flat 

 connective-tissue cells, which wrap around the axone and corre- 

 spond to the endoneurium of the nerve trunk (see page 426). The 

 majority of the axones of the cells of the sympathetic ganglia fall 

 under this category. 



2. Medullated Axones (medullated or myelinated nerve fibres). 

 — These, like the non-medullated, are subdivided according to the 



