Histochemical, Histomorphometrical And Ultrastructural Studies Of Beta-Cells And Exocrine Gland Of Mice Pancreas in Pregnancy And Postpartum Periods

The pancreas is one of the accessory organs that contributes secretion to the digestive tract .It performs many functions that are responsible for blood glucose homeostasis by secreting hormones with differing and opposing effects . Its endocrine portion(islets of langerhans) adapts to changing insulin demands in the body, one of the most amazing reversible islets of langerhans adaptation occurs during pregnancy and lactation. During pregnancy, β-cells mass expand by increasing their number and size . and they are rapidly reversed at end of pregnancy by β- cell apoptosis to retain the normal level . The present study was designed to analyze and compare the general histomorphological changes that happen in the whole pancreas during pregnancy and lactation as well as the ultrastructural changes in β- cells. The pancreas specimens were taken from thirty mature females mice, ten for each group. They were divided into :
Group ( A) served as control.
Group (B) pregnant group( at day 15th of pregnancy)
Group (C) lactating group(at day 4th postnatal).
Tissues were processed for both paraffin block and semithin plastic sections and tissue sections were stained with:
- Haematoxylin and Eosin stain( to demonstrate the general histological and morphological changes that happen) .
Gomori trichrome stain( to differentiate between the islets cells).
Nuclear differentiation stain( to detect the nuclear changes in the islets cells).
Stain for transmission electron microscopy(to study the ultrastructural features of islets cells) .
Two digital image analysing soft wares were used in this study
ImageJ program ( for morphometrical measurement of islets parameters) .
ImageScope program( for assessment of β- cells mass).
Result of the general histological examination of the present study was showed that the acini became larger and their cells had more granules and vacuoles with increase in the size of vacuoles during pregnancy and was demonstrated that the increment in number and size of islets of langerhans were the main features observed during pregnancy and this increment caused by hypertrophy and hyperplasia of β-cells. The result of this work also showed that apoptosis of β -cells started to restore the β - cell number to normal level during lactation . Result of the ultrastructural examination of this study was showed striking morphological changes observed in the secretory granules of β- cells during pregnancy regarding their number, size , shape and density. Result of the morphometric analysis of the islets parameters in this study showed highly significant differences among the studied groups with P value ≤ 0.001. In comparison among the studied groups, the mean number , mean diameter and mean area of islets were significantly higher in pregnant group, intermediate in lactating group and lowest in control group. In this study, the result also showed that the β-cell mass rose near the doubled at 15th of pregnancy in pregnant group as compared with control group, then decreased by 25% at 4th day of postpartum in lactating group as compared with pregnant group.this study conclude that both exocrine and endocrine pancreatic tissues are subjected to natural compensatory changes during pregnancy then they retain to normal state when pregnancy ended