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. 2020 Jan 23;9:e52572. doi: 10.7554/eLife.52572

Figure 4. Catecholaminergic C1 neurons project to the pFRG region.

Figure 4.

(A) Experimental design. (B) Single case showing a positive injection of the retrograde tracer CTb (1%, 30–50 nL) into the pFRG region. (C, D) Photomicrography of catecholaminergic (TH, red) and CTb (green)-labelled cells located in the RLVM and cNTS of one rat with CTb-positive injection into pFRG. White arrows indicate some examples of double labeled cells, whereas the blue arrow indicates the high magnification double label (CTb+/TH+) in the RVLM region. (E, F) Number of CTb and/or TH-labeled cells in the RVLM and cNTS (N = 5). Cell count was obtained in coronary brain sections (six sections from the RVLM and three sections from the cNTS, each of 40 μm thickness with 240 μm of intervals between slices) from each rat. Abbreviations: cNTS, commissural nucleus of the solitary tract; CTb, Cholera Toxin b; pFRG, parafacial respiratory group; RVLM, rostral ventrolateral medulla; Sp5, spinal trigeminal tract; TH, tyrosine hydroxylase; VII, facial motor nucleus. Scale bars in panel (B) = 0.5 mm and in panel (D) = 50 μm (this scale bar applies to panels [C] and [D]).