Comparison of proliferating activity in terminal villi of normal and diabetic placenta

Introduction: Placenta is a unique organ growing during its whole existence. In the last trimester it is expressed first of all by development and growth of terminal placental villi and their capillary bed. Comparing the normal and diabetic term placenta we have found out a higher degree of capillary branching in diabetic terminal villi.

Aim: In this pilot study we tested the hypothesis that this phenomenon is connected with higher proliferating activity of cells constituting capillary wall.

Material and methods: Specimens collected by systematic random sampling from five normal placentas and five placentas form pregnancies complicated by type I diabetes were fixed in formalin and embedded in paraffin. Histological sections were cut from five randomly chosen blocks per placenta and immunohistochemical detection of Ki-67 antigen as a marker of proliferation was performed. The number of Ki-67 positive nuclei was counted in trophoblast, stroma and capillary wall and the area of terminal villi was measured in 20 fields of view per section using Leica IM 500 program.

Results: The Ki-67 labeled nuclei occurred in cytotrophoblast, villous stromal cells and in cells of capillary wall. The mean numbers of positive nuclei in cytotrophoblast, stromal cells as well as in cells of capillary wall per squared millimeter of section were found higher in diabetic placentas but the results were not significant due to great variability of data.

Conclusions: Larger groups of placentas have to be assessed in order to compare the proliferating activity in norma and diabetes, and to test the correlation of this parameter with the level of metabolic control, mode of delivery and sex of newborn.

Supported by the GAČR, project number 304/09/0733.