Exploring processes of organization of normal and neoplastic epithelial tissues in gradient culture.

The biology of animal cells in culture is often studied in individual cells or in sheets of cells. The relevance of such studies to the intact animal is unclear, since the spatial conditions encountered by cells in animals is one of dense three-dimensional masses of cells, with limits to migration, and with gradients both of diffusion of metabolites and of morphologic maturation. These spatial requisites have gradually been met in culture. A brief account describes sponge matrix culture for three-dimensional growth and unilaminar, bilaminar, and radial histophysiologic gradient cultures. Some of the common neoplastic abnormalities of surface epithelial tissues are considered. Proposals for investigating the histokinetic mechanisms regulating some epithelial tissue processes are suggested. In the most recent development of gradient culture methods, a thin permeable transparent collagen membrane is intrinsically strengthened by producing a waffle membrane pattern for histophysiologic gradient culture.