Response of the pial circulation to fatty emboli studied by cinemicrophotography

1. 1. Cinemicrophotographic studies, through a port in the skull, were made of the response of the pial circulation in the monkey to emboli. 2. 2. Dynamic effects upon vessels of from 200 to 20 micra were recorded. 3. 3. Neither a generalized nor localized vasoconstriction was observed to occur in the vessels studied. 4. 4. Arteries and veins expanded segmentally as globular and elongated fat particles traversed the vessels. This expansion permitted passage of an embolus much larger than the vessel involved. 5. 5. Emboli appeared in the large veins (150 micra) seconds after their appearance in the arteries. Many were of large size (25 micra). Dilatation of the capillary bed or arteriovenous shunts may permit the passage of emboli from the arteries to the veins. 6. 6. Through the application of this tool, perfected to permit higher magnification, more information concerning cerebral blood flow should become available.