Pre and postganglionic innervation of rat adrenal gland by fluorescent tract tracer – Fast blue

Abstract Introduction To search for pre and postganglionic neurons innervating the adrenal gland by injecting retrograde tract tracer fast blue in the adrenal medulla. Methods The motor innervation of rat adrenal gland was studied by a fluorescent tract tracer fast blue. 5 μl of 2% aqueous suspension of fast blue was injected into left adrenal gland. After a survival period of 4–5 days, spinal cord, sympathetic ganglia, suprarenal ganglion, coeliac ganglion and left adrenal gland were dissected out and 15 μm thick plastic sections (JB4 Polysciences) were examined under a fluorescent microscope. Results Retrogradely labeled preganglionic neurons were observed in the ipsilateral intermediolateral column of spinal cord from T3 to L2 spinal segments with maximum concentration of labeled neurons from T6 to T11. The labeled neurons were multipolar, spherical or fusiform in shape with transverse diameter 10–20 μm and vertical diameter varying from 12 to 30 μm. Postganglionic labeled neurons were also observed in the left suprarenal ganglion and left sympathetic ganglia (T5 –L2) with maximum concentration from T6 to L1. Labeled neurons varied from 12 to 30 μm in diameter and were randomly distributed throughout the ganglion. Discussion The preganglionic neurons from T3 to L2 spinal segments and postganglionic nerve fibers from ipsilateral sympathetic ganglia (T5 –L2) and suprarenal ganglion supplying the adrenal gland might be responsible for the hormone release by regulating blood flow and also by directly innervating the parenchymal cells.