Tubular bodies of human endothelial cells in an extracellular location.

The specimen was surgically obtained from a 37 year old female with a cerebellar tumor. The diagnosis of this tumor is still inconclusive, because light microscopic and ultrastructural examination of the tumor showed features that were compatible with either hemangioblastoma or renal cell carcinoma metastatic to the cerebellum. Tubular bodies have heretofore been described as being restricted to an intracytoplasmic location in endothelial cells. Discharge of tubules from these organelles into the vascular lumen and the presence of tubules in the extracellular space between an endothelial cell and a pericyte were observed ultrastructurally in vessels from this tumor. Although this report dealt with only a single pathological case, these findings would support a reasonable postulate of discharge of tubular bodies or their tubules into the extracellular space.