ABSTRACT
The hair follicle consists of several approximately cylindrical and concentric cell layers, and these layers are at a low level in a mouse follicle. Electron microscopic studies over 30 years ago yielded a detailed picture of the protein structures that develop in the follicle cells in all the layers of the follicle. This chapter summarizes the proteins that are found in the different cells of the follicle to highlight the several differentiation pathways of follicle keratinocytes. The isolation and sequencing of many keratin genes enables them to be used as transgenes and potentially to express them specifically in their normal location in the hair follicle, provided the coding regions are accompanied by the necessary control regions in the transgene construct. The importance of growth factor genes in hair growth means that their overexpression or ablation should also allow the investigation of their roles in hair follicle morphogenesis and the growth of hair.
