Inflammatory changes were produced in the human skin by means of: (1) physical trauma (cellophane tape stripping); (2) application of a primary irritant (phenol); (3) sensitization (2,4,dinitrochlorobenzene). An ointment containing nicotinic acid was used as a vasodilator substance.
Changes of the minute cutaneous vessels were observed and photographed. A modified technique of capillary microscopy, using vertical illumination and a dipping cone, is presented.
A pattern of vascular reaction emerged which followed its course regardless of the type of injury used. The degree to which this pattern was followed seems to depend upon the amount of damage produced.
The pattern of reaction could be divided into four phases: ( 1) opening of closed vessels; (2) vascular damage; (3) vascular proliferation; (4) vascular recovery.
There is not always a correlation between the gross appearance of the stimulated area and the microscopic anatomic vascular change, as demonstrable by the present technique.