212 



KERATIN AND K ER AT IN I Z ATI ON 



keratinized zone 



zone of keratinization 



zone of fibrillation 



zone of differentiation 



and growth 



germinal matrix 



Fig. 90. The location diagram for the series of figures (Figs. 90-97) 

 illustrating the development of keratiaization in the human hair follicle. 

 On the left-hand side are indicated the several zones A-F into which the 

 cortex is divided. In the growing follicle (centre) (1), (2) and (3) indicate 

 the cortex (and cuticle), the inner root sheath and the outer root sheath, 

 respectively. The cell shapes are those of the presumptive cortical cells. 

 On the r.h.s. is shown a " club root " or non-growing follicle to indicate 

 the extent to which the growing tissues may be resorbed (see also Fig. 40). 



