Endocrine and Neuroendocrine Tumours
Eleni Armeni, Natasha Light, P.N. Plowman, Márta Korbonits, Ashley Grossman
Abstract
In 1966, Pearse first described the cytochemical and ultrastructural properties that were shared by several apparently disparate cell series in the body—initially adrenomedullary chromaffin cells, enterochromaffin cells, the corticotroph, the melanotroph, the pancreatic islet β-cell, and the thyroid C cell. Pearse later proposed the generic name APUD for these cells from the initial letters of their common cytochemical characteristics, which include Amine Precursor Uptake and Decarboxylase activity within the cells (1). Since then, the list of APUD cells has expanded enormously. The structural and chemical similarity of APUD cells to neurons suggested a neural crest origin. Indeed, APUD cells of the adrenal medulla and carotid body are of principally neuroectodermal lineage, and the ultrastructural similarity is true for all APUD cells, although we now know that many such cells develop in situ. Pearse considered these cells as “neuroendocrine” programmed cells derived from determined precursors arising in the embryonic epiblast, or in one of its principal early descendants. They are best conceived as constituting a diffuse neuroendocrine system (DNES), which may be regarded as a third division of the nervous system, the products of which suppress, amplify, or modulate the activities of the other two divisions (2–4).