THE USE OF INDIA INK AND CR-51-LABELED MICROSPHERES IN EXAMINING THE FUNCTION OF THE YOLK STALK AS A PASSAGEWAY BETWEEN THE YOLK-SAC AND INTESTINE IN POSTHATCH BROILER CHICKS

India ink and radioactive Cr-51-labeled microspheres were used in sepa rate trials to examine the role of the yolk stalk lumen as a distinct pathway between the yolk sac and gut through the first 5 d of posthatc h growth In broiler chicks. Throughout this Period, India ink was able to pass from the yolk sac through the yolk stalk and into the intesti ne, but was not able to pass from the intestine into the yolk stalk or yolk sac. Furthermore, labeled microspheres moved from the yolk sac v ia the yolk stalk into the gut; which caused the total counts per minu te of the intestine, yolk stalk, and excreta to progressively increase . It was concluded that India ink and Cr-51-labeled microspheres were useful materials in establishing that the yolk stalk provides a direct one-way passage by which material in the yolk sac may move into the i ntestine of broiler chicks during the first 5 d after hatching.