Neurohistochemical evaluation of adrenergic innervation in fetal development of the white rat

Physiological development of adrenergic innervation, an important component of trophic and homeostatic regulation in the mammals was estimated. Our research is directed to evaluate both exo- and endogenous factors contributing to its impairment. The present investigation was carried out on 32 rat fetuses from three various 7-day periods of gestation. Histochemical studies included reactions to catecholamines according to Falck and Owman, and silver staining with AgNO3 according to the Bielschowsky-Gros method. Adrenergic innervation was examined in all fetal body regions, with a special reference to the pelvis. Catecholamines distribution and accumulation in plexuses, ganglia, neurons and chromatophilic cells, as well as serotonine content in mast cells were analyzed. It was found that in the initial period of gestation noradrenaline is absent. In the third week of gestation, the neurotransmitter's accumulation takes place to subsequently decrease gradually until the end of gestation. From this stage synaptic connections of adrenergic innervation with chromatophilic and mast cells could be detected.