HISTOCHEMICAL-DEMONSTRATION OF PHOSPHOLIPID CONTAINING CHOLINE IN THECYTOPLASM OF MURINE DECIDUAL CELLS

The localization of lipids in the endometrium of virgin and 6- to 9-da y-pregnant mice was detected by histochemical methods. Total lipids (a s shown by staining with Sudan black) and phospholipids containing cho line (PCC) were detected. Sections subjected to reactions that have be en proposed for the demonstration of vitamins E and D and cholesterol gave negative results. In the virgin animals, lipids were found in epi thelial cells but not in the endometrial stroma. On the other hand in the pregnant animals, the endometrial stroma contained both Sudan-blac k-stained lipids and PCC. Maximal staining was reached on day 8 of pre gnancy. The staining was more conspicuous in the more differentiated d ecidual cells adjacent to the embryos than in the less differentiated predecidual cells. The nondecidualized stroma, situated peripherally n ear the myometrium did not stain for lipids. In the cytoplasm of decid ual cells the reaction for PCC was observed in the form of granules, w hich were often arranged in groups surrounding the nuclei. We suggest that decidual cells store PCC to be mobilized as a precursor for media tors of decidualization, such as prostaglandins, that would act as par acrine inducers of the decidual reaction.