Microvascular casting of the lung: vascular lavage.

Corrosion casting is an important tool for the study of microvascular structure, but unlike tissue preparation for light and electron microscopy, few controlled studies of the methods for preparation of microvascular casts for scanning electron microscopy have been reported. Most vascular casting begins with rinsing cells from the lumen of the blood vessels, but the necessity of this has not been shown. Because of a report of successful casting without rinsing and light microscopic evidence of edema with complete rinsing prior to casting, this preparation procedure was examined. Casts of lung vasculature that were thoroughly rinsed were compared to those that were not. Of the six rats that were not lavaged, only one gave a completely filled cast, but of the six animals that were well rinsed, only one did not fill. Except for the filling and mild periarterial edema, no significant difference in cast quality or features was detected. Rinsing improves the frequency of obtaining completely filled casts. The edema does not greatly interfere with the capillary image and its location gives insight into this process in the lung.