Alterations of the connective tissue components induced by β-aminopropionitrile

The ultrastructural and biochemical alterations induced by β-aminopropionitrile on aorta, lung, and skin of 7-day-old chicks have been studied. The inhibition of elastin formation by β-aminopropionitrile was associated with: (i) apposition of elastin on the old fiber in the form of button-like appendices; (ii) absence of microfibrils around this 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 fibroblasts and smooth muscle cells in aorta. The role of lysyl 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.