Abstract
In previous work with the diabetic (DM) pregnant rat we found placentas to be larger and fetuses smaller than normal. To study cellular differences that might contribute to the disparity in size and function of DM placentas, we analyzed by light and electron microscopy DM and control placentas on days 14, 18, and 22 (term). DM was induced using IV streptozotocin (45 mg/kg).
DM placentas (days 18 and 22) were marked by the presence of large numbers of glycogen-distended cells in the junctional zone. The trophoblastic layers in the interhemal membrane were also significantly thicker in the DM group, and large accumulations of lipid droplets were prominent. Since there is normally a striking thinning of the labyrinthine placental barrier by day 22, the thickness of age-matched DM placentas is more impressive, and possibly increases the diffusion distance in the DM placentas. Moreover, 22-day DM placentas contained more glycogen and rough endoplasmic reticulum in the inner trophoblastic layer, a feature similar to 18-day control placentas.
Thus, DM placentas have a number of features that are normally seen earlier in gestation. Histologic evidence confirms increased glycogen and lipid in both the junctional zone and in the cellular barrier between maternal and fetal blood. We speculate that the thickening and modifications of the cellular barrier in DM may affect fetal growth and nutrition by increasing the diffusion distance between the maternal and fetal circulations.
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Gewolb, I., Merdian, W., Warshaw, J. et al. 263 HISTOLOGIC ABNORMALITIES IN THE DIABETIC RAT PLACENTA. Pediatr Res 19, 154 (1985). https://doi.org/10.1203/00006450-198504000-00293
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DOI: https://doi.org/10.1203/00006450-198504000-00293