SENSORY NERVE-ENDINGS. 



179 



trafusal tendon fasciculi. The capsule is continuous at the prox- 

 imal and distal ends of the end-organ with the internal periten- 

 dineum of the tendon in which it is found. The number of the 

 intrafusal tendon fasciculi varies from eight to fifteen or even more. 

 They are smaller than the ordinary tendon fasciculi, from which 

 they originate by division, and structurally resemble embryonic 

 tendon, in that they stain more deeply and present many more 

 nuclei than fully developed tendon. The intrafusal tendon fasciculi 

 are surrounded by an axial sheath of fibrous tissue, between which 

 and the capsule there is found a periaxial lymph-space. 



r 



J 



Fig. 147. Cross-section of neurotendinous nerve end-organ of rabbit ; from tissue 

 stained in methylene-blue : m, Muscle-fibers ; t, tendon ; t, capsule of neurotendinous 

 end-organ ; m n, medullated nerve-fiber (Huber and DeWitt, " Jour, of Comp. Neurol.," 

 vol. X). 



The termination of the nerve-fibers ending in these end-organs 

 has been studied by Golgi, Cattaneo, Kerschner, Kolliker, Pansini, 

 Ciaccio, Huber and DeWitt. One, two, or three large medullated 

 nerve-fibers, surrounded by a sheath of Henle, end in each end- 

 organ ; as they pass through the capsule, the sheath of Henle 

 blends with the capsule. The medullated nerve-fibers before enter- 

 ing the capsule usually branch several times, branching further 

 within the capsule and axial sheath. Before the resultant branches 

 terminate on the intrafusal tendon fasciculi, the medullary sheath is 



