Intimal asteroid bodies in horses: light and electron microscopic observations

The morphology of asteroid bodies in equine arteries is demonstrated by light microscopy as well as by scanning and transmission electron microscopy combined with chemical analysis. Asteroid bodies first occur in horses at four weeks of age in all investigated tissues except the esophagus and always are located in the subendothelial space. The number, shape, ultrastructure and chemical composition of asteroid bodies differ markedly--depending on the age of the horse. Asteroid bodies are round and smooth in foals, but are shaped irregularly and have several projections and marked stratified calcification in adult horses. Asteroid bodies probably originate from smooth muscle cells. No direct etiological connection between asteroid bodies and migrating Strongylus vulgaris could be verified.