The labyrinth layer samples were fixed in 2.5% glutaraldehyde dissolved in 0.1 M phosphate buffer (pH 7.4) for 24 h at 4°C. Following a PBS wash, the samples were fixed with 1% osmium
tetroxide dissolved in 0.1 M phosphate buffer (pH 7.3) for 30 min and dehydrated using a graded series of ethanol concentrations. After the tissues were passed through propylene oxide, they
were embedded in Epon 812. Ultrathin sections were cut, stained with uranyl acetate and lead citrate, and observed using TEM (IOCB, Praha, Czechia, JEM-1011; JEOL).
To measure the area occupied by the Golgi apparatus in the cytoplasm, whole-cell images of the trophoblast giant cells (TGCs) were taken at low magnification. Twenty TGC images were
randomly chosen from each placental sample of three WT and three Nrk KO fetuses. The total Golgi area per cell section was quantified using iTEM image analysis software
(Olympus Soft Imaging Solutions GmbH, Münster, Germany), in which the outline of Golgi stacks and related vesicles was traced manually using a pen tablet device. Student’s
t-test was performed using R ver. 4.2.0.
tetroxide dissolved in 0.1 M phosphate buffer (pH 7.3) for 30 min and dehydrated using a graded series of ethanol concentrations. After the tissues were passed through propylene oxide, they
were embedded in Epon 812. Ultrathin sections were cut, stained with uranyl acetate and lead citrate, and observed using TEM (IOCB, Praha, Czechia, JEM-1011; JEOL).
To measure the area occupied by the Golgi apparatus in the cytoplasm, whole-cell images of the trophoblast giant cells (TGCs) were taken at low magnification. Twenty TGC images were
randomly chosen from each placental sample of three WT and three Nrk KO fetuses. The total Golgi area per cell section was quantified using iTEM image analysis software
(Olympus Soft Imaging Solutions GmbH, Münster, Germany), in which the outline of Golgi stacks and related vesicles was traced manually using a pen tablet device. Student’s
t-test was performed using R ver. 4.2.0.