Figure 12

Anterogradely labeled single spinal afferent axons that co-innervated the myenteric ganglia and the circular muscle in the fundus. (a) Contour of a representative fundus and the location of a single spinal axon within the fundus. (a’) Neurolucida tracing of the axon and the innervated ganglia area (bright blue). (b) Partial projection photomicrograph of the red box in (a’) showed that the varicose fibers coursed on the circular muscle (arrowheads) with collaterals arose from the same spinal neuron innervating the myenteric plexus (arrows). (b1, b2) Single optical sections of the black boxes in (b) showed varicose fibers passing through the ganglion (b1) and coursing on the circular muscle (b2). (c, d) Partial projection photomicrographs of the red box in (a’) displayed varicose fibers terminating in the circular muscle (c, arrow) and traveled within the interganglionic connectives (d). (e, f) Single optical section images of the red box in (a’) showed varicose fibers innervating the myenteric ganglia. PA = parent axon. Scale bar in (a) = 3 mm, in (a’) = 500 μm, in (b) = 100 μm, and in (f) = 20 μm (also applies to b1, b2, c–e).