THE INFLUENCE OF DEXAMETHASONE TREATMENT OF PREGNANT RATS ON THE DEVELOPMENT OF CHROMAFFIN TISSUE IN THEIR OFFSPRING DURING THE FETAL AND NEONATAL-PERIOD

The aim of these examinations was to determine the influence of dexame thasone (Dx)treatment of gravid females, on day 16 of gestation on the development of medullary chromaffin tissue of their fetuses and neona tal offspring. In conducting these investigations we used stereologica l as well as spectrofluorimetric measurements, in 20-day-old fetuses a nd 1-, 3-, 5-, 7-, 9-, 11-, 13- and 14-day-old neonatal rats. Single D x-treatment (1.5 mg/kg bw) of the dams led to a significant decrease i n body and adrenal weight of their fetuses and neonatal offspring, and also reduction of the medullary volume and the number of chromaffin c ells during the entire period examined as a result of decreased cell p roliferation in the fetal and early neonatal period (till the 5th day of age). The proliferative activity of the chromaffin cells was evalua ted through the mitotic index after applying the cytostatic vincristin e-sulphate. During the second neonatal week the mitotic index showed s ignificantly higher values in comparison with the corresponding contro ls, which indicates that there is regeneration and recovery of the adr enal gland medulla. Adrenaline content in the adrenal gland tissue of offspring of Dr-treated dams was significantly reduced only on the Ist neonatal day. Thus, the change in blood glucocorticoid level of pregn ant females after a single Dr injection during the period critical for development of the hypothalamo-pituitary-adrenal system in fetuses af fects the development and kinetics of medullar chromaffin cell divisio n.