The ultrastructural features associated with
vascular permeability in 9 cases of advanced gastric
carcinomas were studied, and compared with that of
control non-neoplastic mucosa. Tumour rnicrovasculature
showed features in common with those of
control mucosa, including complete basa1 lamina, welldeveloped
interendothelial junctions, fenestrations and
caveolae. Some tumour blood vessels showed
endothelial cell swelling accompained by luminal
narrowing and perivascular fibrosis. In 2 out of 9 cases,
there were endothelial attenuation with numerous
fenestrations and vesiculo-vacuolar organelles. The
vesiculo-vacuolar organelle is a recently described
cytoplasmic structure found in the endothelial cells
lining turnour microvessels and normal venules and
which provides an important pathway for extravasation
of circulating macromolecules. Our ultrastructural data
suggest that advanced gastric carcinomas share with
experimental tumour models in vivo only some
morphologic features associated with hyperpermeability
including fenestration, endothelial attenuation and
vesiculo-vacuolar organelles. The implications of
perivascular fibrosis on the delivery of immune cells to
gastric carcinomas are discussed