98 



KERATIN AND KERATINIZATION 



DEVELOPMENT OF THE HAIR CUTICLE 



Fig. 43. A hypothesis of the differentiation of the hair cuticle in terms of 

 the development of intercellular adhesion. 



(a) A germinal cell with poor intercellular adhesion and convoluted 

 (active) membranes. 



(b) The smoothing out and immobilizing of membranes as a result of 

 the appearance of areas of close intercellular adhesion. 



(c) and (d) Complete stabilization of membranes followed by a flatten- 

 ing and tilting due to the spread of adhesion " zipping " the cells together 

 (See also Fig. 44). 



(e) and (f) the commencement of protein synthesis. (From Birbeck 

 and Mercer, 1957). See also Fig. 41. 



