Ultrastructural evaluation of B-cell recruitment in virgin and pregnant offspring of diabetic mothers.

Adult offspring of diabetic rat mothers display a disturbed glucose tolerance and gestational diabetes. The amount of endocrine pancreas and of B-cells is largely sufficient in these non-pregnant and pregnant youngsters. The present work aims a morphometric evaluation of B-cell activity in adult youngsters from control, mildly and severely diabetic mothers, in basal condition and in their adaptation to pregnancy. B-cells are divided, on basis of the ultrastructural morphology of their organelles, in dark non-activated B-cells and pale activated B-cells. These data are related to the concepts of functional B-cell heterogeneity and dose-dependent recruitment of pancreatic B-cells on stimulation. The recruitment of B-cells in each of the groups is evaluated from the proportion pale/dark B-cells. In control animals this is about 50/50, in both experimental groups there is a marked predominance of pale B-cells. During normal pregnancy, a shift occurs towards a majority of pale B-cells. In the offspring of diabetic mothers, the ratio does not further change during gestation. It can be concluded that the disturbance in B-cell stimulation and the development of gestational diabetes in offspring of diabetic mothers is associated with a maximal recruitment of the B-cells already in basal non-pregnant condition.