GLYCOGEN LEVELS IN HUMAN TERM PLACENTAL DISKS, UMBILICAL CORDS, AND MEMBRANES

Glycogen in the placenta and its appendages is important for fetal wel l-being. The precise location of the glycogen stores, however, is unkn own. This study was initiated to quantitate glycogen levels at well-de fined sampling sites in more than 641 samples from 10 uncomplicated pr egnancies and to correlate these glycogen levels with clinical and mor phological variables. By biochemical assay, glycogen levels were great est in the midumbilical cord section (23.08 +/- 1.18 mg/g dry wt) and lowest in the amnionic membrane (2.31 +/- 0.08 mg/g dry wt). Within th e placental dish, parenchymal glycogen levels were greatest near the c ord insertion (9.31 +/- 2.68 mg/g dry wt) and lowest at the periphery (5.71 +/- 1.14 mg/g dry wt). The midumbilical cord glycogen level show ed strong direct correlations (P < .001) with birth weight, umbilical cord weight, and total calculated umbilical cord glycogen and somewhat lower but significant (P < .037) direct correlations with the calcula ted mean umbilical cord glycogen level total calculated placental glyc ogen content, and placental weight. The glycogen level in the middisk parenchymal section from the fetal surface correlated directly with ge stational age. Periodic and Schiff stains showed that magenta glycogen granules were most abundant in the cytoplasm of the vascular smooth m uscle cells. These data show significant variations in glycogen levels among sampling sites. Definition of the precise sampling site is impo rtant for clinicopathologic studies of placental glycogen and for inte rstudy correlations.