Localization of protein in the rabbit yolk sac splanchnopleur by two methods of autoradiography

The distribution of protein labelled with radioactive iodine or tritium within cells of the yolk sac, after it was injected into the uterine lumen of pregnant rabbits, was studied by means of two autoradiographic techniques, one using the classical loop method of Caro & vanTubergen (1962), and the other using Normandin's direct deposition method (Normandin, 1973). The resolution of the latter method was found to be approximately 10 times more sensitive than that of the former (Hemmings & Williams, 1976); thus rendering the site of labelled protein easier to locate. Both techniques are reproducible, but the direct deposition method is easier to handle. Location of protein was detected within vacuoles, and sometimes free in the cytoplasm.