120 



ELEMENTS OF HISTOLOGY. [Chap. xv. 



axis cylinder is prolonged into the interior of the 

 corpuscle. Occasionally the medullated nerve-fibre 

 passes, as such, into the corpuscle, being at the 

 same time more or less convoluted. Having passed 

 to near the distal extremity, it branches, and termi- 

 nates with small enlargements (Krause, Longworth, 

 Merkel, Key and Retzius). 



The end-bulbs in the genital organs, or the genital 

 corpuscles of Krause, are similar in structure to the 

 simple end-bulbs. They occur in the tissue of the 

 cutis and mucous membrane of the penis, clitoris, and 

 vagina. 



156. The corpuscles of Oraiidry or toucJi- 

 corpuscles of Merkel, in the tissue of the papillae in the 

 beak and tongue of birds, are oval or spherical cor- 

 puscles of minute size, possessed of a very delicate 



Fig. 75. Corpuscles of Grandry in the Tongue of Duck. 



A, Composed of three cells ; B, composed of two cells j c, showing the develop- 

 ment of a Grandry 's corpuscle from the epithelium covering the papilla; 

 e, epithelium ; n, nerve-fibre. (Iztiuierdo.) 



nucleated membrane as a capsule, and consisting of a 

 series (two, three, four, or more) of large, slightly- 

 flattened, granular-looking, transparent cells, each with 

 a spherical nucleus, and arranged in a vertical row (Fig. 

 75). A medullated nerve-fibre enters the corpuscle from 

 one side, and losing its medullary sheath, the axis cy- 

 linder branches, and its branchlets terminate, according 

 to some (Merkel, Henle), in the cells of the corpuscle 



