NORMAL HISTOLOGY. 



stratum intermedium, that is ordinarily represented by only a single row of 

 cells to which the name strattim granulosum is usually applied. This layer 

 marks the level at which the conversion of the epithelial elements into horny 

 plates begins and also that at which the separation effected by blistering- 

 usually occurs. On the palms and soles, where the epidermis attains not only 

 great thickness but also higher differentiation, an additional layer, the stratum 



Stratum corneum 



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FIG. 362. Section of skin from sole of foot, showing layers of epidermis. 



X70. 



lucidum, making four in all, may be recognized. The first two represent 

 the portion of the epidermis endowed with. the greatest vitality and powers 

 of repair, and the last two the horny and harder part. 



The stratum germinativum, or stratum Malpighi, rests upon the 

 outer surface of the corium, by the papillae of which it is impressed and, 

 hence, when viewed from beneath after being separated, commonly presents 

 a more or less evident network of ridges and enclosed pits, the elevations 

 corresponding to the interpapillary furrows and the depressions to the 

 papilla. In recognition of this reticulation the name, rete Malpighi, is 

 sometimes applied to the deepest layer of the epidermis. As in other epi- 

 thelia of the stratified squamous type, the deepest cells are columnar and lie 

 with their long axes perpendicular to the supporting connective tissue. The 

 basal ends of the columnar cells are often slightly serrated and fit into cor- 



