In the vascular systems of the body (blood and lymphatic) it is the smallest muscular vessels that play the greatest role in physiological regulation. It has been extremely difficult in the past to make quantitative studies of the behavior of these vessels because they are too small to allow the attachment of mechanical devices to measure their contractions. It is possible to measure their movement by computer image processing, but this approach has not been exploited because of the previous high cost of the equipment and the lack of suitable software. Now that appropriate computer equipment is no longer prohibitively expensive, we will use a novel algorithm of our design to implement software that will (1) monitor diameter in several separate regions of a vascular tree and (2) monitor diameter change as a function of length along a region of a single vessel. The algorithm we now use can be applied to vessels in isolated preparations that do not contain blood. In response to our own needs and to requests from other groups, we have developed another algorithm for vessels that contain blood, and we shall develop a second set of programs using this algorithm. These systems will advance the technical capabilities in basic research in the fields of blood and lymphatic microcirculation.
