Studies of the distribution of glycogen between the inner cell mass and trophoblast cells of mouse embryos

Abstract

Autoradiographic and histochemical techniques were used to determine the localization of glycogen synthesized during in vitro culture of preimplantation mouse embryos. During early cleavage, embryos accumulated little glycogen and that which was synthesized was spread evenly in the blastomere cytoplasm. Morula and early blastocyst stages accumulated relatively large amounts of glycogen, especially in the peripheral or trophoblastic cells in comparison to the inner cells or inner-cell-mass cells. Immunosurgical techniques were used to study the incorporation of radiolabeled glucose into the biochemical pools of inner-cell-mass and trophoblastic cells during culture for 24 h. Trophoblastic cells incorporated considerably more isotope than did inner-cell-mass cells, especially into the acid-soluble glycogen fraction. Inner cell masses isolated on day 4 of pregnancy incorporated more glucose into acid-soluble glycogen than did inner cells isolated from blastocysts at the end of culture for 24 h in isotope.