Figure 3

Light and electron micrographs of abdominal and gastric branches of human vagus nerve. (A) LM overview of a representative abdominal vagus nerve from a 49 year old female. Note multiple fascicles surrounded by loose connective tissues and lipid droplets (arrows). Scale bar = 100 µm. (B, C) Detailed view of individual fascicles indicated by yellow and red boxes in (A). Note outline of perineurium of each fascicle (arrows) and intermittent presence of myelinated axons within each fascicle. Scale bar in B = 25 µm; Scale bar in C = 10 µm. (D). Fascicle in (C) after segmentation of the inner and outer contours of myelinated axons (n = 22) and perineurium. Quantitative information in (E–J) are derived from contoured structures in (D). (E) Histogram of percent of fascicle area inside of perineurium occupied by myelinated axons. (F–H) Size distribution of myelinated fiber diameter, axon diameter, and myelin thickness, respectively. (I) Distribution of G-ratios for myelinated fibers. (J) Histogram of perineurium thickness ratio. (K, L) Electron micrographs of unmyelinated axons of the abdominal vagus nerve in 52 year old male. (K) Note Remak bundle formed by Schwann cell with nucleus viewed as two portions (SC) in this plane of sectioning and two unmyelinated axons. (L) Schwann cell nuclei (SC) with associated unmyelinated axons surrounded by collagen fibers. Note basal lamina (arrows) outlining the cell membrane of each Schwann cell. Scale bar in K, L = 2 µm.