C14 Assays and Autoradiographic Studies on the Rooster Comb

The distribution of C(14) was studied in various parts of the rooster comb following treatment with testosterone. The value of gas-phase assay of C(14) in tissue has been demonstrated and the results compared with those of autoradiographic studies on the same tissue. The results of these experiments showed that androgen treatment significantly increases the rate of incorporation of C(14) in various parts of the comb. The specific activity of carbon in the comb, cornea, and liver differed, depending on which precursor, viz. glucose-6-C(14), glucose-1-C(14), and glucuronolactone-U-C(14), was administered. The highest values were obtained after the administration of glucose-6-C(14); glucuronolactone-U-C(14) gave the lowest specific activity. The specific activity of carbon in different parts of the comb showed considerable variation. Carbon assay of serial sections of the comb cut at various planes showed that the specific activity of carbon was highest in the mucoid layer. Both C(14) assays and autoradiograms indicate that C(14) is also present in other parts of the comb. As seen in autoradiography, the concentration of C(14) was highest in the epithelium, in the blood vessel walls, and in the avascular collagenous tissue. These results, and indications from previous studies, suggest that the high specific activity of carbon in the mucoid layer is due mainly to the presence of C(14)-labelled hyaluronic acid. Autoradiograms and PAS staining suggest that a significant amount of C(14) is also incorporated into the glycoproteins associated with the collagen fibers.