Light- and electron-microscopic observations of theophylline-induced aortic aneurysms in embryonic chicks

• Published in: The American journal of pathology Vol. 112; no. 3; pp. 258 - 266
• Main Authors: Yokoyama, H, Matsuoka, R, Bruyere, HJ, Jr, Gilbert, EF, Uno, H
• Format: Journal Article
• Language: English
• Published: Bethesda, MD ASIP 01-09-1983; American Society for Investigative Pathology
• Subjects: Animals; Aorta - ultrastructure; Aortic Aneurysm - chemically induced; Aortic Aneurysm - pathology; Biological and medical sciences; Blood and lymphatic vessels; Cardiology. Vascular system; Chick Embryo; Collagen - analysis; Diseases of the aorta; Elastic Tissue - pathology; Elastic Tissue - ultrastructure; Endothelium - pathology; Endothelium - ultrastructure; Heart - embryology; Heart Septal Defects, Ventricular - chemically induced; Heart Septal Defects, Ventricular - pathology; Medical sciences; Necrosis; Sodium Chloride - administration & dosage; Theophylline - administration & dosage; Pathology; Vertebrata; Embryo; Optical microscopy; Experimental disease; Aneurysm; Aorta; Chicken; Aves; Electron microscopy; Aortic disease
• ISSN: 0002-9440; 1525-2191

These investigators have previously developed a model for inducing aortic aneurysms by administering theophylline or caffeine to embryonic chicks. This report describes light-microscopic and ultrastructural changes in aortic walls of theophylline-treated embryos relative to saline-treated controls. Light-microscopic examination of areas of permanent aortic dilatation revealed thinning of the medial layer due to a marked decrease in the number of medial cells. Electron-microscopic observation of aortic walls with aneurysms revealed widely scattered medial cells with scanty cytoplasm containing poorly developed microorganelles, a markedly widened intercellular space with dispersed elastic and collagen fibers in the tunica media, and a disruption of endothelial cells. It is suggested that the induction of aortic aneurysms by theophylline in chick embryos may be attributed to two factors: 1) atrophy and subsequent hypoplasia of the aortic media possibly resulting from an elevated intracellular cyclic adenosine 3',5'-monophosphate, which inhibits mitosis in medial cells, and 2) altered hemodynamics due to the action of theophylline on the embryonic heart.