Pericytes are cells of mesodermal origin that intimately surround most types of blood capillaries as well as postcapillary venules and precapillary arterioles (smooth muscle cells are found in the walls of larger vessels). Although abnormalities of capillary endothelial cells have been described in diseases such as diabetes, arterial hypertension, autoimmune inflammatory myopathies and also in the paraneoplastic phenomenon, much less is known about morphology of pericytes and its implications in the microvascular structure in cancers, particularly those arising in the gastrointestinal tract. In this work we report the pericyte ultrastructural pathology in human gastrointestinal adenocarcinomas.

Surgically resected specimens from areas of tumor center and periphery were obtained from thirteen patients (seven females and six males) between 44 and 76 years of age (mean 61.92 years), with a histopathological diagnosis of gastrointestinal adenocarcinoma. Immediately after resection, tissue samples were processed by routine transmission electron microscopy techniques and observed in Hitachi H-500 and H-7100 electron microscopes.