Morphometric evaluation of the fetal rat liver after maternal dexamethasone treatment: effect on the maturation of erythroid and megakaryocytic cells.

BACKGROUND

During pregnancy, glucocorticoids are frequently used to accelerate fetal lung maturation in preterm delivery. However, prenatal administration of glucocorticoids has been shown to affect organs such as fetal liver, an important hematopoietic organ during fetal development.

OBJECTIVE

The aim of this study was to document the qualitative and quantitative changes in erythroid and megakaryocytic cell populations found in fetal livers as well as the hematology profile in neonates after maternal glucocorticoid treatment in rats.

METHODS

Pregnant female Wistar rats were treated with dexamethasone 21-phosphate from days 13 to 16 of gestation. On the 17th day of pregnancy, the fetuses were collected and their livers processed for light and transmission electron microscopy. Glycol methacrylate-embedded sections were stained with PAS to determine the erythroblast and megakaryocytic cell frequencies. Fetal liver pieces embedded in Spurr resin were analyzed by transmission electron microscopy for morphologic changes. A standard hematology profile was evaluated in neonatal rats.

RESULTS

In the fetuses from treated dams, the total cell number of erythroid cells in livers was significantly reduced compared to control fetuses (P < .001), but erythroblasts did not present ultrastructural abnormalities. The degree of maturation in the megakaryocyte series tended to be increased. In neonates, there were elevated numbers of nucleated RBCs (P = .002), along with a higher HCT and HGB (P = .02). In addition, the platelet concentration was also significantly increased (P < .007).

CONCLUSION

These results suggest that maternal dexamethasone treatment has quantitative effects on erythroid and megakaryocytic cells in fetal liver and the neonatal hematology profile in rats.