"Extraepithelial enterochromaffin cell--nerve-fibre complexes" in the normal human appendix, and in neurogenic appendicopathy.

Extraepithelial, extraglandular endocrine cells of types EC1 and EC2 occur in the lamina propria of the normal appendix. They are more numerous in intramucosal neurogenic appendicopathy. Ultrastructurally there is invariably a close association between the cells and non-myelinated nerve fibres of the mucous plexus. Together they form a complex surrounded by a common basal lamina, and the term enterochromaffin cell-nerve fibre complex (ECC-NF) is suggested for this morphological and functional unit. The derivation of extraepithelial EC cells from the glandular epithelial cells could not be established and the existence of the complexes is held to support an origin from neuroendocrine-programmed ectoblasts.