128 



THE ESSENTIALS OF HISTOLOGY. 



superficial layers are hard and horny, this horny portion sometimes 

 constituting the greater part of the thickness of the epidermis. The 

 deepest cells of the rete mucosum, which are set on the surface of the 

 cutis vera, are columnar (fig. 151, c) in shape. In the coloured races 

 of mankind these cells contain pigment-granules. In the layers 

 immediately above them the cells are polyhedral (fig. 151, p}. 

 Between all these cells of the rete mucosum there are fine intercellular 

 clefts which separate the cells from one another, but are bridged across 

 by fine fibres, which pass from cell to cell, and also through the sub- 

 stance of the cells (Eanvier, Delepine). The intercellular channels 

 serve for the passage of lymph, and within them occasionally lymph- 

 corpuscles may be found, often having a stellate figure from compression. 



FIG. 151. SECTION OF EPIDERMIS. (Ranvier.) 



H, horny layer, consisting of s, superficial horny scales ; sw, swollen-out horny cells ; s.l., 

 stratum lucidum ; M, rete mucosum or Malpighian layer, consisting of p, prickle-cells, 

 several rows deep ; c, elongated cells forming a single stratum near the corium ; and 

 s.gr, stratum granulosum of Langerhans, just below the stratum lucidum ; n, part of a 

 plexus of nerve-fibres in the superficial layer of the cutis vera. From this plexus fine 

 varicose nerve-fibrils may be traced passing up between the epithelium-cells of the 

 Malpighian layer. 



The most superficial layer of the rete mucosum is formed of some- 

 what flattened granular-looking cells (stratum granulosum, fig. 151, s.gr ; 

 fig. 152, c}. Immediately above this layer, the liwny part of the 



