NEUROTRANSMITTERS AND PEPTIDES IN THE DEVELOPING HUMAN FACIAL NUCLEUS

The human facial nucleus can be sub-divided into five structurally dis crete regions. Immunohistochemistry was used to locate various neurotr ansmitters and neuropeptides in the neurons and nerve fibres of the hu man facial nucleus at 14 and 27 weeks of gestation and in the neonate. Whilst choline acetyltransferase-positive neurons were observed in th e facial nucleus at all stages of development, dopamine beta-hydroxyla se-positive neurons were only found in the neonate. In addition, affer ent nerve fibres positive for choline acetyltransferase, enkephalin an d substance P were observed at all stages of development. In the young er specimens these fibres were evenly distributed; however, in the neo nates the fibres were asymmetrically distributed as the different type s became concentrated in the various structurally distinct regions of the facial nucleus.