The Acidophilia of Elastin

Conditions relevant to the acceptance of acid dyes by the elastin of the aorta are as follows: (a) Fixation. Cold alcohol is poor, formol-sublimate, hest; others are intermediate. (h) Acid dyes used. Bromphenol blue is best, light green is poor, acid fuchsin is unstable in alkaline solution. Ponceau, aniline blue, fast green, chromotrope, erythrosin, and eosin are only moderately useful. (c) Staining pH. Elastica shares with eosinophil granules the property of retaining acid dye up to pH 11. (d) Autolysis. There is no effect even after 24-36 hr post mortem on acid dye affinity. (e) Speed of staining. Minor variations will appear if staining is less than 30 min. (f) Species of animal. Rat, mouse, cat, sheep, rabbit, guinea pig, opossum, ferret, rhesus monkey, horse, cow, and pig all possess acidophilic aortic elastin. A special feature has been the effect of age on the staining of human aortic elastin; bromphenol blue washes out quickly from the aortic elastin of old subjects, slowly from that of infants.