On the nature and function of organizers

Martínez Arias, Alfonso; Steventon, Ben

doi:http://dx.doi.org/10.1242/dev.159525

On the nature and function of organizers

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Martínez A, Steventon B. On the nature and function of organizers. Development. 2018 Mar;145(5):1-10. DOI: 10.1242/dev.159525

Abstract

Organizers, which comprise groups of cells with the ability to instruct adjacent cells into specific states, represent a key principle in developmental biology. The concept was first introduced by Spemann and Mangold, who showed that there is a cellular population in the newt embryo that elicits the development of a secondary axis from adjacent cells. Similar experiments in chicken and rabbit embryos subsequently revealed groups of cells with similar instructive potential. In birds and mammals, organizer activity is often associated with a structure known as the node, which has thus been considered a functional homologue of Spemann’s organizer. Here, we take an in-depth look at the structure and function of organizers across species and note that, whereas the amphibian organizer is a contingent collection of elements, each performing a specific function, the elements of organizers in other species are dispersed in time and space. This observation urges us to reconsider the universality and meaning of the organizer concept.