3*4 



HISTOLOGY. 



t* 



age they tend to disappear entirely. As seen in Fig. 360 they may be 

 definitely arranged beneath the ridges of the finger tips, forming a double 

 row under each; the grooves between the ridges correspond with epithe- 

 lial depressions between the papillae. In Fig. 361-, which represents the 

 under surface of the epidermis, the relation of the papillae to the rect- 

 angular markings may be seen. The papillae are formed of tunica propria, 

 a cellular connective tissue; and each papilla contains terminal capillary 

 loops or a tactile corpuscle (Fig. 126, p. 105). The corpuscles are most 



numerous in the 

 sensitive finger tips 

 where they may 

 occupy one papilla 

 in every four. 



Beneath the 

 papillae the connec- 

 tive tissue bundles 

 are closely inter- 

 woven but toward 

 the subcutaneous 

 tissue they form a 

 coarse network 

 [hence the corium 

 is sometimes divi- 

 ded into a stratum 

 papillare and a 

 deeper stratum re- 

 ticulare]. The sub- 

 cutaneous tissue is 

 areolar, with large 

 areas of fat cells; 



where the fat forms a continuous layer it is called the panniculus 

 adiposus. Columns of areolar tissue which extend to the hair 

 follicles and glands of the skin, may become paths for infection from 

 the surface to the subcutaneous tissue. The elastic fibers of the skin 

 are said to form a subepithelial net, a thick plexus of fine fibers beneath 

 the papillae, and layers of coarse fibers along the vessels in the deeper 

 part of the corium and in the fascia. The subcutaneous tissue contains 

 relatively little elastic tissue. In the skin of the face and joints, elastic 

 elements are most abundant; in old age, throughout the skin, they decrease 

 notably. Smooth muscle fibers constitute the arrector muscles of the 

 hairs; as a membranous layer they occur only in the tunica dartos of the 



Part of the stratum 



corneum. 



Stratum lucidum. 



Stratum 

 granulosum. 



Stratum 

 germinativum. 



Tunica propria of 



the corium. 



FIG. 362. FROM A SECTION THROUGH THE SKIN OF THE SOLE OF THE 

 FOOT OP AN ADULT MAN. X 360. 



