no 



TEXT % -BOOK OF PHYSIOLOGY. 



In the visceral muscle the terminal nerve- fibers derived from 

 sympathetic or peripheral neurons are primarily non-medullated. 

 axons divide and subdivide and form plexuses which surround 

 the muscle-cell bundles.^, Fine fibers from the plexuses are given off 



Nerve-fiber 

 bundle. 



FIG. 45. MOTOR NERVE-ENDINGS OF INTERCOSTAL MUSCLE-FIBERS OF A RABBIT. 



X 150. 



which ultimately come into relation with each individual cell, on the 



surface of which they terminate in the form of one or more granular 



masses. 



In the glands, taking as an illustration the parotid and mammary 



glands, the nerve- fibers, also derived f rorn^ sympathetic or peripheral 



neurons, pass into the body of 

 the gland and ultimately reach 

 the acini, on the outer surface of 

 which they ramify and form a 

 plexus. From this plexus fine 

 fibers penetrate the acinus wall 



FIG. 46. TERMINATIONS OF NERVE- and end on the gland-cell. The 

 FIBERS IN THE GLAND-CELLS. A. fibers present a varicose appear- 



Cell of the parotid gland of a rabbit. /-p- ^ 



B. Cells of the mammary gland ^i g ' 4 ^ 



of a cat in gestation. (Doyen and The afferent nerves as they 

 Morat.) approach their ultimate termina- 



tions undergo similar changes. 



The end-tufts become associated, in some situations, with specialized 

 end-organs which are extremely complex; e. g., the retina in the eye, 

 the organ of Corti in the ear, the taste-beakers in the tongue, the 

 olfactory cells in the nose. 



