the keratinization process 221 



Metabolic Enzymes 



Certain enzymes concerned with basic cellular metabolism are necess- 

 arily present in all cells and show a diffuse cytoplasmic distribution. 

 Rogers (1953) applied the Nadi reagent as a test for cytochrome oxidase to 

 wool roots and found a strong reaction in the bulb extending to the proxi- 

 mal third of the shaft. Montagna (1956) reports similar findings. Dehy- 

 drogenase activity has been demonstrated by means of tetrazolium salts 

 which are reduced by the enzymes to yield purple granules (see Montagna, 

 1956, for review). Rogers specifically demonstrated succinic, /?-glycero- 

 phosporic, lactic and malic dehydrogenases. 



The oxidases and dehydrogenases are associated with energy-supplying 

 reactions and their presence in the hair bulb could also be associated with 

 mitosis which Bullough (p. 136) has shown requires energy. The dehy- 

 drogenases of the shaft could also be concerned with the energy-consuming 

 process of transport of metabolites from the bulb or of the glycogen from 

 the outer root sheath. A cyclic variation in these enzymes in the epidermis 

 during the hair cycle is described by Carruthers et al. (1959). Presumably 

 also, the energy required for protein synthesis is obtained through similar 

 reactions. Since many of these enzymes are now known to be located in 

 mitochondria, their presence could also be inferred from the mitochondria 

 visible in electron micrographs of these cells. 



Glycogen (Fig. 97 (d)) 



The most conspicuous deposits of glycogen are in the o.r.s. cells. In the 

 middle third of the follicle the cells are virtually filled with it. The possible 

 role of this glycogen as an energy store, which buffers the follicular 

 system against the fluctuations in glucose content of the systemic blood 

 supply and thus enables a steady rate of mitosis to be maintained in the 

 bulb, has been mentioned in Chapter IV. When the hair follicles of rodents 

 are quiescent no glycogen is present, it increases rapidly when growth 

 recommences (Montagna et ai, 1951). In good agreement Ryder (1958) 

 found that radioactive glucose rapidly (1 hr) entered the bulb where it was 

 presumably being utilized directly to sustain mitosis and later was localized 

 (probably as stored glycogen) in the outer root sheath. Bradfield (1951) 

 believed that epidermal cells stored glycogen while in the basal layer and 

 carried it outwards where it supplied energy for protein synthesis in the 

 outer layers. 



Acid Mucopolysaccharides and Schiff-reactive 

 Substances (Fig. 97 (a)) 

 Metachromatically-staining substances (p. 54) are present in the 

 dermal papilla (Sylven, 1950 and 1951; Montagna, 1956) and Schiff- 

 positive material seems to occur in much the same situation (Leblond, 



