C, TEM showed that fragmented luminal epithelial cells with cytoplasmic lipid droplets are engulfed by the trophoblast in the control mice (Rb1f/f mice). Scale bar = 2µm. Arrowhead, cytoplasmic fragments engulfed by trophoblast; yellow dotted line circle, cytoplasmic lipid droplets in the luminal epithelium; red dotted line, stroma; green dotted line, luminal epithelium; blue dotted line, trophoblast. 