Figure 1.

A comprehensive representation of the three main theories about MiNENs’ origin proposed to date. From the left to the right, collision theory, common precursor theory, and trans-differentiation theory are illustrated respectively. As mentioned in the text, the first one suggests that neuroendocrine and non-neuroendocrine components arise independently from distinct precursor cells, the second one postulates a common origin from a pluripotent stem cell progenitor, which differentiates towards both components; finally, the third one assumes that neuroendocrine differentiation is the result of progressive accumulation of genetic alterations in an initially non-neuroendocrine cell phenotype.