Microvascular alterations following cerebral contusion in rats. Light, scanning, and electron microscope study.

Cerebral contusion was caused in 18 rats by dropping various weights on an exposed dura of one hemisphere. One or 3 hours after the injury the animals were sacrificed by perfusion with paraformaldehyde-glutaraldehyde solution. The traumatic microvascular and neural tissue alterations were studied with light, scanning, and electron microscopic techniques. The microvascular obstructions and damage were revealed in this study as major histological alterations, causing secondary neural damage. The obstruction of the vessels appeared to have been caused 1) by extravascular pressure from destroyed and swollen tissue, petechial hemorrhage, and dissecting extraluminal clots; and 2) by intravascular clots. Besides the tearing and shearing effects causing petechial hemorrhages, the capillary walls were often thinned and irregular.