title: Morphology of enkephalin-immunoreactive myenteric neurons in the human gut.
abstract: The aim of this study was the morphological and further chemical characterisation of neurons immunoreactive for leu-enkephalin (leuENK). Ten wholemounts of small and large intestinal segments from nine patients were immunohistochemically triple-stained for leuENK/neurofilament 200 (NF)/substance P (SP). Based on their simultaneous NF-reactivity and 3D reconstruction of single NF-reactive cells, 97.5% of leuENK-positive neurons displayed the appearance of stubby neurons: small somata; short, stubby dendrites and one axon. Of these leuENK-reactive stubby neurons, 91.3% did not display co-reactivity for SP whereas 8.7% were SP-co-reactive. As to their axonal projection pattern, 50.4% of the recorded leuENK stubby neurons had axons running orally whereas in 29.4% they ran anally; the directions of the remaining 20.2% could not be determined. No axons were seen to enter into secondary strands of the myenteric plexus. Somal area measurements revealed clearly smaller somata of leuENK-reactive stubby neurons (between 259+/-47 microm(2) and 487+/-113 microm(2)) than those of putative sensory type II neurons (between 700+/-217 microm(2) and 1,164+/-396 microm(2)). The ratio dendritic field area per somal area of leuENK-reactive stubby neurons was between 2.0 and 2.8 reflecting their short dendrites. Additionally, we estimated the proportion of leuENK-positive neurons in comparison to the putative whole myenteric neuron population in four leuENK/anti-Hu doublestained wholemounts. This proportion ranged between 5.9% and 8.3%. We suggest leuENK-reactive stubby neurons to be muscle motor neurons and/or ascending interneurons. Furthermore, we explain why we do not use the term "Dogiel type I neurons" for this population.
authors.affiliation: Institute of Anatomy I, University of Erlangen-Nuremberg, Krankenhausstr. 9, 91054, Erlangen, Germany. axel.brehmer@anatomie1.med.uni-erlangen.de
authors.forename: A
authors.initials: A
authors.lastname: Brehmer
authors.forename: T M
authors.initials: TM
authors.lastname: Lindig
authors.forename: F
authors.initials: F
authors.lastname: Schrödl
authors.forename: W
authors.initials: W
authors.lastname: Neuhuber
authors.forename: D
authors.initials: D
authors.lastname: Ditterich
authors.forename: M
authors.initials: M
authors.lastname: Rexer
authors.forename: H
authors.initials: H
authors.lastname: Rupprecht
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004743:Enkephalin, Leucine / Q000032:analysis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007420:Intestine, Large / Q000737:chemistry* / Q000166:cytology; D007421:Intestine, Small / Q000737:chemistry* / Q000166:cytology; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D008875:Middle Aged; D009197:Myenteric Plexus / Q000737:chemistry* / Q000166:cytology; D016900:Neurofilament Proteins / Q000032:analysis; D009474:Neurons / Q000737:chemistry*; D013373:Substance P / Q000032:analysis
chemical_list: D016900:Neurofilament Proteins; C051774:neurofilament protein H; D013373:Substance P; D004743:Enkephalin, Leucine