Renaissance in the Microcirculation

Inquiry into the nature and the function of the microcirculation began shortly after Harvey postulated the existence of "porosities of the flesh" in 1628.Although the critical importance of the microcirculation was evident from the start, research in the area has been characterized by brief periods of activity and long periods of neglect.August Krogh (1) noted in his introduction to the Silliman Lectures in 1922 that before 1915 most physiology texts contained only a few lines on the subject of capillaries and histology texts all but ignored the topic.He also observed that interest in the capillaries grew substantially after that time with a number of laboratories simultaneously and independently taking up work in the area.In the years following Krogh's studies, the capillaries and the associated small vessels continued to occupy the attention of a number of laboratories that were using a variety of direct and indirect experimental approaches.Progress in the field was hampered, however, by the virtual absence of quantitative techniques which could be used in microscopic studies.As a consequence most researchers interested in quantifying microcirculatory function chose methods which involved measurement of total vascular function in an organ or a region.The past few years, however, have seen a renaissance of interest in microscopic studies of the microcirculation accompanied by a