Arterio-venous Differences in Plasma Calcium Concentration in the Shell Gland of the Laying Hen during Shell Formation

Abstract

THE site of shell mineralization in the bird has been established to be the oviduct shell gland or uterus. Eggs laid via a fistula posterior to the shell gland are completely calcified, whereas those laid via a fistula anterior to this organ lack shell mineralization; partial resection of the shell gland leads to a proportionate decrease in the quantity of mineral deposited in the shell (Asmundson and Jervis, 1933). Richardson (1935) has shown that the shell gland epithelium does not appear to function as a calcium storage organ. He attributes the calcium excretion associated with shell formation to increased circulation in the shell gland in conjunction with the increased calcium concentration of the circulating blood. However, a thickening of the surface layer of the shell gland cells was observed during shell formation, indicating some associated tissue changes. Descriptions of the shell gland structure are available (Bradley and Grahame, 1950; Romanoff . . .