THE INNERVATION OF THE ADENOHYPOPHYSIS IN THE DUCK

Abstract

SUMMARY The innervation of the adenohypophysis in the duck has been investigated by means of the Bielschowsky-Gros technique. An autonomic nervous formation, termed the plexus hypophyseus, is present in the connective tissue surrounding the pituitary and in all parts of the gland itself. This formation is composed of large strands of nerve fibres with ganglion cells and of delicate ones belonging to the autonomic end-formation—the sympathetic ground-plexus (Boeke). The sympathetic ground-plexus is a part of the plexus hypophyseus and extends from the capsule of the pituitary into the pars distalis, pars tuberalis and neural lobe. Small ganglia, distributed through the strands of the plexus hypophyseus and termed ganglia hypophysea, are situated immediately adjacent to the parenchyma of the pars distalis. Small ganglion cells are also present in the pars distalis and pars tuberalis. In addition, a dense nervous secreto-motor end-plexus, specifically innervating the gland cells of the pars distalis, is described and its possible functional significance discussed. The origin of the nerve fibres of this end-plexus is not established.