THE EPIDERMIS 



267 



The cells of the granular layer are flattened and angular. They 

 possess an indistinct, apparently degenerating nucleus, and their cyto- 

 plasm contains large plate-like granules of Tceratoliyalin (eleidin of 

 Eanvier), which are strongly basophil and stain readily with most 

 nuclear dyes. 



Eleidin-containing Layer (Stratum Lucidum). The granule cells 

 are abruptly transformed into the shiny cells of the stratum lucidum, 

 which is the deepest layer of the horny portion of the epidermis. The 

 colls of this layer possess an indistinct nucleus, are irregularly flattened 

 and angular in shape, are more or less fused together at their adjacent 

 margins, and contain a smooth, highly refractive, glassy cytoplasm which 

 reacts feebly to most a 



staining reagents, but is 

 deeply colored by safranin. 



The stratum lucidum 

 is so named because of its 

 highly refractive appear- 

 ance; it is usually about 

 two cells thick. Its cyto- 

 plasm contains eleidin, a 

 substance which is prob- 

 ably intermediate in chem- 

 ical composition between 

 the keratohyalin of the 

 stratum granulosum and 

 the keratoid pareleidin of 

 the horny cells. 



Flattened Cell Layer 

 and Scaly Layer (Stra- 

 tum Corneum and Stra- 

 tum Disjuncium of Ran- 

 vier). Above the stratum 

 lucidum the horny layer 

 consists of flattened corni- 

 fied cells which are closely 

 packed and somewhat fused and blended with each other at their faintly 

 serrated margins. Intercellular bridges and spaces have almost entirely 

 disappeared. The nuclei of the cells are no longer demonstrable, and 

 their cytoplasm has been changed into a dry, shiny, highly refractive 

 mass of ' keratin' (pareleidin) which responds but slightly to ordinary 



FIG. 264. TRANSECTION OF THE EPIDERMIS OF THE 

 FOOT. 



a, superficial scaly layer; b, layer of flattened 

 cells, the inner and outer portions of which have 

 been characteristically blackened by osmium tet- 

 roxid; c, stratum lucidum; d, granular layer; e, 

 prickle cells; /, cylindrical cells; g, papillary layer 

 of the derma. Osmium tetroxid, carmin. Moder- 

 ately magnified. (After Ranvier.) 



