Plate 14 



A. Cross-section of human-hair follicle in the pre-keratin zone to show 

 the whorl-like arrangement of the fine filaments in the fibrils, F. The fine 

 filaments may show a hexagonal packing (H) in the centre of the fibrils 

 which changes towards the fibril periphery to resemble a spiral (S). 

 Notice the filaments are embedded in a denser ground substance. For an 

 enlargement showing this detail, see Plates 15 and 16. At Cu appears a 

 portion of a cuticle cell containing irregular lumps of cuticular keratin 

 devoid of fine structure. 



B. Section running approximately parallel to the basement membrane in 

 the epidermis of a frog tadpole. Centrally it passes into the epidermal cell 

 and whorls of "keratin" fibrils, /, are seen; nearer the edges of the 

 picture the section passes obliquely through the basal membrane, BM. 

 Note the pattern of dense desmosomal studs D and the finer granular 

 deposits a. Surrounding this are seen the dermal collagen fibrils in quasi- 

 orthogonal array. For a section at right angles to this, see Plate 9. PTA 

 stain. 



