Abstract
The adrenergic innervation of the thoracic lymphatic duct was studied in young, mature and old animals. Adrenergic innervation of lymphatic system in postnatal ontogenesis, especially in its late period, was not thoroughly studied. The purpose of this study was to determine the state of adrenergic innervation of TLD in young, mature, and senile animals. The study shows that the adrenergic apparatus in the TLD tissues of rats continues its formation and complication from the first days after birth and is entirely formed by Day 25–30 after birth. From the age of one month, the adrenergic innervation represents fully formed plexuses in all areas which function throughout life. These are brightly fluorescent nerve fibers that form plexuses with regularly located multiple sites of varicose dilation. In senile animals, the dilations remain frequent and numerous in all parts of the lymph node, but their brightness decreases; the fibers in the plexuses become discontinuous, the varicose thickenings become less frequent or disappear. The adrenergic vasomotor innervation in the walls of the TLD affects its function. The formed adrenergic innervation is presented across all periods of postnatal ontogenesis of the TLD and affects its functioning, and age-related changes in the course of development and aging of the organism can be considered as adaptation to new conditions. This study promotes understanding of the sympathetic regulation. The trial does not involve people and the trial registration is not required.