Localization of Gallium–67 During Embryogenesis

Abstract

Summary

Isotope uptake in embryos and tissues of pregnant mice was determined 24 hr after intravenous inoculation of pregnant mice with either ⁶⁷Ga or [³H]TdR. ⁶⁷Ga concentration in embryos and associated maternal tissue at 6–8 days was comparable to values reported previously in normal adult mouse tissues, whereas in embryos at 9–11 days, it equaled or surpassed concentrations reported in leukemic tissues of adult AKR and BALB/c mice. By Day 13, ⁶⁷Ga counts were diminished in the embryos. The ⁶⁷Ga concentration in the thymus of pregnant mice decreased progressively with increasing gestation time, as did [³H]TdR uptake in embryonic tissue. Autoradiograms revealed that the ⁶⁷Ga localized in fetal membranes, limb buds, and vertebrae of the embryos and in the decidua. Conversely, embryos and de–cidua labeled with [³H]TdR indicated no such selectivity. ⁶⁷Ga did not localize in crypt cells of the intestinal tract, whereas [³H]TdR did. Therefore, incorporation of ⁶⁷Ga in the fetal tissues and decidua did not appear to be related to DNA synthesis. In addition, ⁶⁷Ga localization during embryogenesis may prove to be a useful model system for determining the basis and general significance of ⁶⁷Ga localization in nonosseous tissues.