106 



THE ESSENTIALS OF HISTOLOGY 



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

 immediately above them the cells are polyhedral (fig. 129, 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. The intercellular channels 

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

 corpuscles may be found, often having a stellate figure from compres- 

 sion. The most superficial layer of the rete mucosum is formed of 

 somewhat flattened granular cells (stratum granulosum, s.gr}. Iin- 



sw 



n 



FIG. T29. SECTION OF EPIDERMIS. 



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 granulosuni of Langerhans, just below the stratum lucidum ; , 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. 



mediately above this layer, the horny part of the epidermis commences, 

 as a layer of clear compressed cells several deep (stratum lucidum, s.l.}. 

 Above this comes the main part of the horny layer. It is composed of 

 a number of layers of somewhat swollen cells (sw.'), the nuclei of 

 which are no longer visible. These cells become flatter as they 

 approach the surface, where they eventually become detached in the 

 form of thin horny scales (s). 



The growth of the epidermis takes place by a multiplication of the 



