Differential adhesion hypothesis

The differential adhesion hypothesis (sometimes called the "thermodynamic hypothesis") is a theory of cell adhesion advanced by Malcolm Steinberg in 1964 to explain the mechanism by which heterotypic cells in mixed aggregates sort out into isotypic territories. The DAH postulates that tissues are viscoelastic liquids, and as such possess measurable tissue surface tensions. These surface tensions have been determined for a variety of tissues, including embryonic tissues and cell lines. The surface tensions correspond to the mutual sorting behavior: the tissue type with the higher surface tension will occupy an internal position relative to a tissue with a lower surface tension (if these tissues can interact with each other through their adhesion machinery). Quantitative differences in homo and heterotypic adhesion are supposed to be sufficient to account for the phenomenon without the need to postulate cell type specific adhesion systems: fairly generally accepted, although some tissue specific cell adhesion molecules are now known to exist.

=References=
 * 1) http://www.biology-online.org/dictionary/Differential_adhesion