The problems

Abstract

The cells of every living organism are in a continuously dynamic but stable state of flux, both within and between the chemical, genetic and cellular levels. There is always a constant flow of molecules in and out of the metabolic pathways, controlled partly by chemical and partly by genetic feedback mechanisms, and in multicellular organisms there is also usually a constant flow of tissue cells which pass from their birth in mitosis to their death in cellular old age. It is the latter phenomenon of cell flow that is the main theme of this book, and because mammalian epidermis is easily accessible, and its cells are ideally stratified, with mitosis basally and cell death distally, this is the main tissue considered here.