Fig. 2. Developmental expression of NO induced cGMP-IR in MG neurons and NADPH diaphorase staining of the midgut epithelium. (A) At about 60% of embryonic development (% E), the MG neurons (mg) formed a cellular packet at the foregut-midgut boundary (vertical line indicates boundary). Caeca (ca) were not stained. At this stage, all MG neurons began to show strong anti-cGMP staining. In the ingluvial ganglion (ig), some neurons expressed sGC activity (lateral view). (B) Between 60 and 65% E, the first MG neurons started to migrate posteriorly on the midgut surface. All MG neurons showed high levels of anti-cGMP staining. (C,D) Between 60 and 65% E, NO-sensitive sGC activity was expressed in the cell body and the advancing processes of the leading MG neurons. (E) At 60% E, first NADPH-diaphorase staining was present in distinct cells of the midgut. The inset of the designated area shows an example of NADPH-diaphorase-positive cellular staining. The first appearance of the diaphorase staining was coincident with the onset of MG neuron migration (compare to A with B). (F) Anti-cGMP-IR at 65% E; lateral view. At this stage, anti-cGMP IR was present in cells of the ingluvial ganglion, the enteric nerves and the foregut neurons (fg). Some of the midgut neurons migrated laterally to form a nerve ring near the foregut-midgut boundary. (G) At 70% E, the MG neurons were still migrating posteriorly. The leading as well as the following neurons of one migratory pathway showed strong cGMPIR. (H) During the phase of lateral neurite branching and the formation of terminal processes on the midgut musculature, the MG neurons continued to exhibit strong cGMP-IR. These micrographs were compiled from several focal planes. Scale bars: 50 µm in A,B; 20 µm in C,D; 200 µm in E,F; 25 µm in G,H.

Return to article