Neurotransmitters and peptides in the developing human facial nucleus

The human facial nucleus can be sub-divided into five structurally discrete regions. Immunohistochemistry was used to locate various neurotransmitters and neuropeptides in the neurons and nerve fibres of the human facial nucleus at 14 and 27 weeks of gestation and in the neonate. Whilst choline acetyltransferase-positive neurons were observed in the facial nucleus at all stages of development, dopamine beta-hydroxylase-positive neurons were only found in the neonate. In addition, afferent nerve fibres positive for choline acetyl-transferase, enkephalin and substance P were observed at all stages of development. In the younger specimens these fibres were evenly distributed; however, in the neonates the fibres were asymmetrically distributed as the different types became concentrated in the various structurally distinct regions of the facial nucleus.