86 



NORMAL HISTOLOGY. 



FIG. 104. 



Genital corpuscle from the 

 human clitoris ; this ending 

 represents a group of partly 

 fused simple spherical end- 

 bulbs : n, nerve-fibres entering 

 the capsule. (After Krause.) 



spheroidal form of those already considered. Just as in the preceding 

 group, so here the simpler endings lead from the tactile cells to the 

 more highly specialized structures ; the cylindrical end-bulbs of the 

 conjunctiva of the calf are the simplest members 

 of this group, while the corpuscles of Vater, or 

 the Pacinian bodies, are its most highly special- 

 ized representatives. 



The nerve-endings of this class are composed 

 of three parts the cap- ( 

 FIG. 105. sule, the inner bulb, 



and the nerve-fibre. 

 Upon the arrangement 

 and development of these 

 the differences distin- 

 guishing the individual 

 endings chiefly depend. 



In the simpler forms 

 of end-bulbs, as those 

 found in the conjunctiva 

 and the oral mucous 

 membrane of certain 

 mammals, the body is 

 borne upon a stalk, which 

 contains the medullated nerve-fibre and, possibly, a minute blood- 

 vessel enveloped in connective tissue. The sheath of Henle invest- 

 ing the nerve is prolonged into 

 the nucleated capsule. The latter 

 encloses a conspicuous cylindrical 

 mass of granular or faintly striated 

 pale substance the inner bulb 

 within which the free axis-cylinder 

 lies, terminating often in a slightly 

 marked knol^ike expansion. The 

 medullary .^fbstance ends where 

 the nerve^fibre enters the inner bulb. 

 Furth^-coTflplexity in the struct- 

 ure of the end-bulbs is largely 

 due to elaboration of the capsule ; 

 this latter becomes laminated and 

 very thick, while the inner bulb 

 likewise exhibits new details of 

 structure. Since the intermediate 

 forms in the series of end-bulbs do not occur in man, the highly 

 specialized corpuscles of Vater, or the Pacinian bodies, may at 



Simple spherical end- 

 bulb from the human con- 

 junctival mucous mem- 

 brane : , the medullated 

 nerve-fibre which disap- 

 pears within the capsule. 

 (After Krause.) 



FIG. 106. 



Simple cylindrical end-bulbs from the scleral 

 conjunctiva of calf : n, nerve-fibre passing into 

 the inner bulb (b) ; K, neurilemma which, with 

 perineurial sheath (C), continues as the capsule, 

 C'. (After Schiefferdecker .) 



