Abstract
Diabetes mellitus (DM) is a chronic metabolic disease in which the body fails to produce enough insulin or increased tissue resistance to insulin. The diabetes may have profound effects on placental development and function. This study was designed to detect the placental changes in pregnancy associated with DM comparing these changes with normal placenta. The study was carried out on sixty full-term placentae; divided into three equal groups; control group (group I): placentae of normal pregnancy, uncontrolled diabetes (group II): placentae from pregnant women whose blood glucose is poorly controlled during pregnancy. Controlled diabetes (group III): includes placentae from diabetic women whose blood glucose is controlled during pregnancy. The placentae from group II tend to be heavier and exhibited immaturity of villi, villous edema, fibrosis, excessive syncytial knots formation and infarctions. In addition to, fibrinoid necrosis, increased thickness of vasculo-syncytial membrane, syncytial basement membrane, microvillous abnormalities and vascular endothelial changes were demonstrated. The syncytial multivesicular knots were present in placentae of group II. The nuclei within these syncytial knots display condensed chromatin, either dispersed throughout the nucleus or in the form of dense peripheral clumps with and numerous cytoplasmic vacuoles. The syncytial basement membrane showed focal areas of increase in its thickness and irregularity. Villous cytotrophoblasts showed increased number and activity in the form of numerous secretory granules, abundant dilated RER, larger distorted mitochondria. Villous vessels showed various degrees of abnormalities in the form of endothelial cell enlargement, folding, thickening and protrusion of their luminal surfaces into vascular lumen making it narrower in caliber. In placentae of group III, most of these abnormalities decreased. In most of placentae of group III, the VSM appeared nearly normal in thickness and showed nearly normal composition of one layer of syncytiotrophoblastic cells, one layer of smooth, regular capillary endothelium and the space between them. Mild microvillous abnormalities were noted in few placentae as they appeared short and blunted with mild decrease in their number per micron.
The electron picture of syncytial knots appeared nearly normal containing aggregations of small, condensed hyperchromatic nuclei, minimal vacuoles could be seen in the cytoplasm of syncytial knots. Syncytial basement membrane appeared regular and nearly normal in its thickness and composition coming in direct contact with fetal blood capillaries but mild abnormalities were noted in the basement membrane in few placentae as increased its thickness and deposition of fibers or fibrinoid. Regarding cytotrophoblasts in the terminal villi of placentae with controlled diabetes, these cells appeared nearly normal. They were scattered beneath the syncytium and were active containing mitochondria, rough endoplasmic reticulum, free ribosomes and a large nucleus with fine dispersed chromatin. The vascular ultrastructural pattern in terminal villi of placentae of this group showed no significant abnormalities and was normally distributed in the villous tree. The luminal surface of the vascular endothelium appeared regular smooth in the majority of placentae of this group. The endothelial cells appeared connected to each other with tight junctions. It could be concluded that whether if long-term diabetes is controlled or not, placentae of diabetic mother showed a variety of significant histological structural changes seen more frequently than in the placentae of pregnant women without diabetes.