Hurwitz, S., Department of Animal Science, The Volcani Institute of Agricultural Research, Rehovot, Israel, Department of Biology, Bar-Ilan University, Ramat Gan, Israel
Cohen, I., Department of Animal Science, The Volcani Institute of Agricultural Research, Rehovot, Israel, Department of Biology, Bar-Ilan University, Ramat Gan, Israel
Bar, A., Department of Animal Science, The Volcani Institute of Agricultural Research, Rehovot, Israel, Department of Biology, Bar-Ilan University, Ramat Gan, Israel

1. 1. An electrical potential difference (PD) of about 10 mV, with the serosal surface positive with respect to the mucosa, was demonstrated in vitro with uteri from chickens and Japanese quail. 2. 2. PD was higher during the period of shell secretion than in the inactive uterus. 3. 3. Nitrogen atmosphere, musocal 2,4-dinitrophenol and serosal ouabain depressed the PD in both species. 4. 4. A requirement of metabolizable hexose for maintenance of the PD was established. 5. 5. The existence of a sodium pump in the uterine wall is suggested. © 1970.