CONNECTIVE TISSUE CHANGES IN THE ROOSTER COMB DURING REGRESSION

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Abstract
Comb growth was induced in White Leghorn capons by daily treatment with testosterone propionate for 15 days. The hormone treatment was then discontinued and the regression of the romb in the course of the following 24-days period studied in respect to the content of hyaluronic acid, water and various protein fractions. Comb size measurements and histological studied showed that regression of the comb is accompanied by reduction and finally disappearance of the so-called mucoid layer, which gives positive histochemical tests for the presence of acidic glycosaminoglycans. Chemical analysis revealed that the hyaluronic acid content of the comb is reduced to practically zero in the course of the regression period, parallel with a considerable loss of water. A significant correlation was observed between the hyaluronic acid content and comb weight, as well as between hyaluronic acid and water content. The disappearance of hyaluronic acid from the comb was found to fit a semilog linear regression line, with a period of 5 to 9 days required to reach half of a given value. The relationship of this result to the biological half-life time of hyaluronic acid in the steady state is discussed. The relative rise in the total protein content of the comb in the course of regression was attributed to the dehydration of the comb. Only minor changes were observed in the protein composition. The collagen content showed a slight decrease during the second half of the regression period, suggesting a delayed onset of collagen breakdown, as compared with the immediate response of the hyaluronic acid and water content. The soluble protein fraction of the comb was found to be correlated with the comb weight and remained constant in concentration; electro-phoretic and immunological analysis showed this fraction to be partly identical with serum proteins. No direct relationship was observed between the hyaluronic acid and this protein fraction.