1 3 86 



HUMAN ANATOMY. 



: -r. 



Stratum corneum 



Stratum lucidum 



Stratum 



granulosum 



Stratum 



germinativum 



Deepest cells 



of epidermis 



Corium 



Portion of preceding preparation, showing in more detail layers of epidermis 

 only deeper part of stratum corneum is represented. X zbo. 



interpapillary furrows and the depressions to the papillae. In recognition of this 

 reticulation the name, rete Malpighi, is sometimes applied to the deepest layer of 

 the epidermis. As in other epithelia of the stratified squamous type, the deepest cells 



are columnar and lie with 

 their long axes perpen- 

 dicular to the supporting 

 connective tissue. The 

 basal ends of the colum- 

 nar cells are often slight- 

 ly serrated and fit into 

 corresponding indenta- 

 tions on the corium. 

 Their outer ends are 

 rounded and received 

 between the super- 

 imposed cells. Succeed- 

 ing the single row of 

 columnar elements, the 

 cells of the stratum 

 germinativum assume a 

 pronounced polygonal 

 form, but become some- 

 what flatter as they 

 approach the stratum 

 granulosum. The num- 

 ber of layers included 

 in the germinal stratum 

 is not only uncertain, 

 but varies with the rela- 

 tion to the papillae, being greater between than over these projections. The finely 

 granular cytoplasm of the cells of the stratum germinativum contains delicate but 

 distinct fibriUce, which, longitudinally disposed in the deep columnar cells, in the 

 polygonal elements (Fig. 1151), radiate from the nucleus towards the periphery 

 (Kromayer). The fibrillas are not confined to the cells, but extend beyond and pass 

 across the intercellular lymph -clefts as delicate protoplasmic bridges that connect 

 the units of the various layers of the stratum and confer upon them the character- 

 istics of the so-called ' ' prickle cells. ' ' 



The stratum granulosum is exceptionally well marked on the palms and soles 

 and in these localities includes from 

 two to four rows of polygonal cells, 

 somewhat horizontally compressed, 

 that stand out conspicuously in stained 

 sections by reason of the intensely 

 colored particleswithin theircytoplasm. 

 The nature of the peculiar substance, 

 deposited within the body of the cells 

 as particles of irregular form and size, 

 is still uncertain. To it Ranvier gave 

 the name of eleidin and Waldeyer that 

 of koatohyalin. Since the nuclei of 

 the cells in which the deposits occur 

 always exhibit evidences of degenera- 

 tion, it is probable that keratohyalin 

 is in some way derived from disintegra- 

 tion of the nucleus (Mertsching) and 

 represents a transition stage in the 



process ending in cornification of the succeeding layers of the cuticle (Brunn). 



The stratum lucidum, usually wanting in other localities, in the palm and 



sole appears as a thin, almost homogeneous layer, separating the corneous from the 



FIG. 1151. 





Fihrillre 



Intercellular, 

 cleft 



Portion of horizontal section of skin, showing intracolliilar 

 fibrillre within cells of stratum germinativum. X 800. 





