Nervous control of the gills

The fishgillisahighlycomplexorganthatperformsawidevarietyofphysiological
processes andreceivesextensivenervousinnervationfrombothafferent(sensory)
and efferent(motor)fibres.Innervationfromthelattersourceincludesautonomic
nerve fibresofspinal(sympathetic)andcranial(parasympathetic)originwhose
primary roleistoinducevasomotorchangeswithintherespiratoryornonrespiratory
pathways ofthegillvasculature.Autonomiccontrolofthegilloccursbynervefibres
identified asadrenergic,cholinergic,andmorerecentevidenceindicatesthat
nonadrenergic–noncholinergic (NANC)nervefibres,suchasthosethatexpress
amines, peptides,ornitricoxide,mayalsoplayanimportantrole.Thedistribution
and physiologicalfunctionofNANCnervefibres,however,islessclear.Thisreview
primarily discusseshistochemicalstudiesthathavecharacterizedthenervous
innervation andautonomiccontrolofthegillvasculature.Inaddition,supporting
evidence fromrecentstudiesfortheefferentcontrol,ormodulation,ofother
homeostatic processesinthegillisexamined.