Figure 2.

XII motoneurons retrogradely labeled from the base of the tongue and dopamine β-hydroxylase (DBH)-positive terminals located in the ventromedial quadrant of the XII nucleus in a pair of matched for anteroposterior level brain sections from (A) chronic intermittent hypoxia (CIH)- and (B) sham-exposed rat. (A1, B1) Low-magnification images of the XII nucleus, with rhodamine-labeled XII motoneurons (brown) located mainly in the ventromedial part of the nucleus. A 100 × 100 μm box was placed in this region for counting of DBH-positive terminals (black). (A2, B2) High-magnification images of the counting boxes shown in A1 and B1. Only a small fraction of DBH-positive varicosities contained within the boxes can be seen (those that are within the focal plane of this photograph). (A3, B3) Redrawing of retrogradely labeled XII motoneurons and all DBH-positive terminals contained in the counting boxes shown in panels A2 and B2. Red dots show DBH axonal varicosities found to be closely apposed to labeled XII motoneurons (gray); black dots show all remaining DBH terminals found throughout the depth of these brain sections.