SENSORY NERVE-ENDINGS. 



173 



lamellated capsules are relatively large structures. We shall con- 

 sider especially the Vater-Pacinian corpuscles, the neuromuscular 

 end-organs, and the neurotendinous end-organs. 



Vater-Pacinian Corpuscles. These corpuscles are of oval shape 

 and vary much in size, the largest being about o. 10 of an 

 inch long and 0.04 of an inch broad. The greater portion of the 

 corpuscle is made up of a series of concentric lamellae, varying 

 in number from twenty to sixty. These lamellae are made up of 



Fig. 140. Vater-Pacinian corpuscle from the mesentery of a cat; X 45- The 

 figure shows a general view of the corpuscle, a, Axis-cylinder in the core ; ik, core ; 

 tnn, medullated nerve-fibers entering the core (" Atlas and Epitome of Human His- 

 tology," Sobotta). 



white fibrous tissue fibers, rather loosely woven, between which is 

 found a small amount of lymph, containing usually a few leucocytes. 

 The lamellae are covered on both surfaces by a layer of endothelial 

 cells (Schwalbe). Between two consecutive lamellae there is found an 

 interlamellar space, also containing lymph. The axis of the cor- 

 puscle is occupied by a core, consisting of a semifluid, granular 

 substance, in the periphery of which oval nuclei are said to be 

 found. Usually one large medullated nerve-fiber goes to each cor- 

 puscle. The fibrous tissue sheath of this nerve-fiber becomes con- 

 tinuous with the outer lamellae of the capsule. The medullary 

 sheath accompanies the axis-cylinder through the concentric lamel- 

 lae until the core is reached, where it disappears. The naked axis- 

 cylinder usually passes through the core to its distal end, where it 

 divides into three, four, or five branches which terminate in large, 

 irregular end-discs. The axis-cylinder may, however, divide soon 

 after it enters the core into two or three or even four branches, 

 these passing to the distal end of the core before terminating in the 

 end-discs above mentioned. Both Retzius and Sala state that the 

 naked axis-cylinders, after entering the core, give off numerous short 

 side branches, terminating in small knobs, which remind these ob- 

 servers of the fine side branches or thorns seen on the dendrites of 

 Purkinje's cells and of the pyramidal cells of the cortex, when stained 



