Epithelia are one of the commonest tissue types in the animal kingdom. Chapters from leading scientists in the major international research laboratories use examples from different systems to illustrate the form and function of epithelia. An important theme is the way in which epithelial cells differentiate to specialized tissue - reversal of this process occurs when cells become tumorigenic.Epithelia are one of the commonest tissue types in the animal kingdom. Chapters from leading scientists in the major international research laboratories use examples from different systems to illustrate the form and function of epithelia. An important theme is the way in which epithelial cells differentiate to specialized tissue - reversal of this process occurs when cells become tumorigenic.The establishment and maintenance of hepatocyte surface polarity - J R Bartles; Cell adhesion and intercellular junctions in cultured epithelial cells - D R Garrod and J Collins; Instructive cell-cell adhesion and membrane cytoskeleton assembly in development of epithelial cell surface polarity - H McNeil and W James Nelson; The formulation and fate of the blastoderm epithelium in the Drosophila embryo - R Warn and M Robert-Nicoud; The role of the yolk sac and gut epithelial cells in maternal immunoglobulin transport - A E Wild; Protein and lipid targeting and the generation of epithelial cell polarity - E Rodriguez-Boulan and S K Powell; Trophectoderm biogenesis in the preimplantation mouse embryo - T Fleming. Development of kidney epithelial cells - L Sorokin, G Klein, G Mugrauer, M Ekblom, L Fecker and P Ekblom; The epithelial cell and its microenvironment: an integrated unit of function. Evidence from the mammary gland - R S Talhouk, Z Werb and M Bissel; Epithelial cell interactions with the basement membrane in regulation of early events in skin morphogenesis - W G Carter, T A Brown, M C Ryan an B E Symington; The development of a simple epithelil£‡