Alterations of the connective tissue components induced by beta-aminopropionitrile

The ultrastructural and biochemical alterations induced by beta-aminopropionitrile on aorta, lung, and skin of 7-day-old chicks have been studied. The inhibition of elastin formation by beta-aminopropionitrile was associated with: (i) apposition of elastin on the old fiber in the form of button-like appendices; (ii) absence of microfibrils around the abnormally deposited elastin; (iii) presence of ruthenium red and toluidine blue O-positive material within the lathyritic elastin; (iv) increase of proteoglycan content; (v) increase of the mean diameter of collagen fibers; (vi) increased vesiculation of the endoplasmic reticulum of both fibroblast and smooth muscle cells in aorta. The role of lysysl oxidase in the assembly of elastin and collagen fibers is discussed. Particular attention has been paid to the relationship between elastin, microfibrils, and proteoglycans in the formation of the elastic fiber.