The community effect, a controversial concept in embryology

The "community effect" has been termed after the British embryologist J.B. Gurdon as a cooperation between cells of identical type that is required for their determination or the completion of differentiation. The introduction of this concept was necessary for Gurdon since it may be of general significance in embryology. Actually, community effects have been found in a variety of systems in Xenopus, Drosophila, the zebra fish and the mouse. However, this concept is not widely used and the molecular basis for the community effect remains to be understood. The study of a mutation affecting the coat colour of mice has uncovered a community effect among melanoblasts after the colonization of the hair follicle at the end of embryogenesis. The identification of the gene responsible for this;phenotype should help understanding the mechanisms responsible for a community effect.