262 



NORMAL HISTOLOGY. 



anterior aspects, and thicker on the outer side ol the limbs than on 

 their mesial surfaces. 



The epidermis, or the cuticle, is a highly developed stratified 

 squamous epithelium ; while forming a protecting layer to the 

 underlying sensitive corium over 

 the entire surface of the body, the FIG. 300. 



epidermis varies in different regions, 

 in some places, as on the eyelids 

 and brow, not exceeding . i mm. in 

 thickness, while in others, as on the 

 soles of the feet and the palms of 

 the hands, it reaches almost i mm. 

 The epidermis is accurately adapted 

 to the opposed surface of the corium, / 

 which is beset with papillae, so that 

 when the two layers are separated 



Epidermis of human skin separated from corium, 

 viewed from beneath : a, thickened areas filling de- 

 pressions between papillae ; b, pits receiving papillae 

 of corium ; c, ducts of sweat-glands. 



Section of human skin from hand, in- 

 cluding superficial layer of corium and 

 epidermis : a, b, c, d, respectively the 

 stratum corneum, lucidum, granulosum, and 

 Malpighii ; e, layer of columnar cells next 

 the corium ; f, fibro-elastic tissue consti- 

 tuting papillary layer of corium. 



the under surface of the epidermis presents impressions or pits 

 corresponding to the elevations of the rorium which they receive. 



The cells composing the epidermis are arranged in many 

 irregular layers, the number of which depends upon the cuticular 

 development in any particular region ; where well represented the 

 layers are grouped into two sharply-defined zones, the inner, darker, 

 softer stratum Malpighii and the outer, clearer, denser stratum 

 corneum ; where highly developed the epidermis presents two 

 additional zones, distinguished by the peculiar character of the pro- 

 toplasm of their cells ; these layers are the stratum granulosum 

 and the stratum lucidum. 



The stratum Malpighii, or rete mucosum, contains the most 



