The capillary circulation of the skin; some normal and pathological findings.

1. Introduction In the past, numerous investigators have studied the structure and function of the microcirculation in vivo. Much of our knowledge concerning minute vessels stems from studies made in lower animals. Various ingenious techniques have been devised for such studies—for example, the rabbit ear chamber of Sandison 1 and of the Clarks 2 or animal mesentery preparations. 3,4 With these methods, the small vessels may be viewed at high magnifications with transillumination, since the vascular bed is situated in one plane in a thin layer of transparent tissue. Unfortunately, these techniques cannot be directly applied in man, and methods using reflected light must be employed. In vivo study of the capillary circulation in man was first described 45 years ago by Lombard, 5 who made direct observations on the nail fold capillaries through a microscope using reflected light. Since then, the majority of studies on the circulation