Shell Strength and Carbonic Anhydrase Activity of the Shell Gland of the Domestic Fowl

INTRODUCTION SINCE Meldrum and Roughton (1933) first suggested that the enzyme carbonic anhydrase in the shell gland of birds might be connected with the formation of the shell, several investigators have produced data supporting this suggestion. Thus it was shown (Common, 1941; Gutowska and Mitchell, 1945) that the carbonic anhydrase activity of the shell gland was lower in birds laying soft shelled eggs, than in birds laying normal shelled eggs. Further, it was shown (Gutowska and Mitchell, 1945) that the production of soft shelled eggs by feeding sulphonamides, also resulted in a suppression of carbonic anhydrase measured in the shell gland. Since sulphonamides act as inhibitors of carbonic anhydrase (Scott et al., 1964; Mehring et al., 1955) these results have been widely held to show that carbonic anhydrase in the shell gland is closely connected with shell formation, presumably by providing carbonate anions for the formation of calcium carbonate of . . .