The enkephalinergic innervation of the genioglossus musculature in the rat: implications for the respiratory control of the tongue.

This study sought to determine if the enkephalinergic (ENK) innervation of the hypoglossal nucleus (nXII) in the rat was organized differentially for the control of the genioglossus musculature whose activity is essential in maintaining the patency of the upper airway. Immunocytochemical results revealed that the genioglossus motoneuron pool, comprising the ventrolateral subcompartment of the nXII, was consistently and heavily labeled throughout its rostrocaudal dimension. Labeling was characterized by dense focal clustering throughout the neuropil, and by the appearance of numerous perisomatic-like profiles.

Pre- and postnatal development of the catecholamine innervation of the hypoglossal nucleus in the rat: an immunocytochemical study.

The pre- and postnatal development of the catecholamine (CA) innervation to the hypoglossal nucleus (nXII) in the rat was investigated immunocytochemically with antisera to tyrosine hydroxylase (TH). Immunoreactive profiles positive for TH were first identified in nXII on gestational day (GD) 16. By GD 18, the adult-like distribution pattern was evident, characterized by the preferential targeting of the ventromedial region of nXII, but this pattern was not consistently found in all fetuses until GD 19.

Subcompartmental organization of the ventral (protrusor) compartment in the hypoglossal nucleus of the rat.

The extent and myotopic organization of the ventral (protrusor) compartment of the hypoglossal nucleus (nXII) in the rat is controversial. Of particular concern is the location of motoneurons that innervate the intrinsic (verticalis, transversus) as compared to extrinsic (genioglossus) tongue protrusor muscles. These issues were investigated with retrograde transport, lesion/degeneration/immunocytochemical, and classic Golgi staining techniques.

Sources of noradrenergic afferents to the hypoglossal nucleus in the rat.

The sources of noradrenergic (NA) innervation to the hypoglossal nucleus (nXII) in the rat were investigated with double-labeling histochemical/immunocytochemical and lesion/degeneration techniques. Following injection of wheat germ-agglutinin conjugated to horseradish peroxidase into nXII, brain stem sections were reacted with tetramethylbenzidine, stabilized, and incubated in antiserum to tyrosine hydroxylase (TH). Double-labeled neurons were observed in three pontine sites bilaterally, although mainly ipsilaterally, that included the nucleus subceruleus (nSC; 68.

Topographically organized projections from the nucleus subceruleus to the hypoglossal nucleus in the rat: a light and electron microscopic study with complementary axonal transport techniques.

Projections from the nucleus subceruleus (nSC) to the hypoglossal nucleus (XII) were investigated with complementary retrograde and anterograde axonal transport techniques at the light and electron microscopic level in the rat. Injections of WGA-HRP into XII resulted in labeling of neurons in and around the nSC. Labeled nSC neurons were few in number (less than 4 per 40-60 microns sections) and variable in size and shape.