Morphometry of peptide-containing nerves in gut muscle layers: a quantitative approach to the study of autonomic neuro-muscular junctions

Abstract A method for the quantitative assessment of peptide-containing nerves in the gastrointestinal muscle layers is described. Tissue samples are sectioned obliquely, at 45°, in the plane bisecting the long axes of longitudinal and circular muscle fibres, and peptide-containing nerve fascicles are revealed by immunofluorescence. Cross-sectioned fascicles are counted (number/area of muscle) and their length density per volume of muscle layer is calculated. The composition of immunostained nerve fascicles is also assessed, by counting peptide-containing fibres in each, while peptide transmitter co-distributions are studied in parallel using adjacent tissue sections. Thus, the approach described provides a means for the delineation of both quantitative tissue distribution and composition of autonomic neuro-muscular junctions in the gastro-intestinal tract.