Distribution of VGLUT-containing peripheral nerve fibers in mouse visceral organs and the MPG. Immunofluorescence ((a)–(c), (g)–(i)) and bright-field ((d)–(f)) photomicrographs of sections of the colorectum ((a)–(c), (d)–(f)) the urinary bladder ((g), (h)) and the MPG (i), incubated with VGLUT₁ ((a), (h)) or VGLUT₂ ((b), (c), (h), (i)) antibodies or VGLUT₁, VGLUT₂ or VGLUT₃ antisense riboprobes ((d), (e), (f), resp.). In (i), a colorectal MPG NP is exposed by its content of fast blue (asterisk). In ((a), (c), (g) and (h)), the position of the lumen is indicated by a white asterisk. ((a)–(c)) Isolated VGLUT₁-IR nerve fibers are detected in the mucosal layer of the colorectum (double arrowhead in (a)), in contrast to the abundance of VGLUT₂-IR nerve fibers in the myenteric plexus (black double arrowheads in (b)), the interconnecting nerve fibers (white double arrowheads in (b)), and the mucosal layer (white double arrowheads in (c)). ((d)–(f)) Only a number of VGLUT₂ mRNA-expressing myenteric plexus NPs are detected in the mouse colorectum (black double arrowheads in (e)), in contrast to the absence of VGLUT₁- or VGLUT₃ mRNA-expressing NPs in such ganglia ((e), (f), resp.). ((g), (h)) While a small number of VGLUT₁-IR nerve fibers are detected in the urinary bladder wall, especially in the muscular layer (black double arrowheads in (g)) and some in the submucosa (white double arrowhead in (g)), VGLUT₂-IR nerve fibers are abundant and present throughout the whole thickness of the organ, including the muscular (black double arrowheads in (h)) and submucosal and mucosal layers (white double arrowheads in (h)). (i) A colorectal MPG NP is surrounded by a dense VGLUT₂-IR basket (white double arrowheads). Scale bars: 50 μm ((a)–(c), (g), (h)); 25 μm ((d)–(f)); 10 μm (i). Figures (d) and (e) are reproduced in part, and with permission, from reference [61]. Data in figure (f) is previously unpublished, and the tissue has been processed according to the in situ hybridization procedures described in [60, 61].