Figure 13

Anterogradely labeled single spinal afferent axons that co-innervated the myenteric ganglia and the circular muscle in the corpus. (a) Contour of a representative corpus and the location of a single spinal axon within the corpus. (a’) Neurolucida tracing of the axon and the innervated ganglia area (bright blue). (b) Partial projection photomicrograph of the red box in (a’) illustrated that the single axon bifurcated into many varicose branches as passageways situated in the myenteric plexus (arrows) and the circular muscle (arrowheads). (b1, b2) Partial projection photomicrographs of the black box in (b) showed varicose fibers innervating the circular muscle and myenteric ganglia. (b1’, b2’) Single optical sections of (b1) and (b2), respectively. (c–f) Partial projection (c, d) and single optical section (e, f) photomicrographs of red boxes in (a’), the axon gave off varicose branches running parallel to circular muscle fibers (c, d; unstained, imaged with DIC) and traveling through the myenteric ganglia (e, f). PA = parent axon. Scale bar in (a) = 3 mm, in (a’) = 500 μm, in (b) = 50 μm, and in (f) = 20 μm (also applies to b1–b2’, c–e).