Fig. 7. FLRFamide labeling in the anterior cardiac plexus consists of peripherally located varicosities derived from large diameter fibers. (A) Confocal micrograph showing the distal termination of the left ACP. Here, several immunolabeled fibers can be seen to project fine processes toward the periphery of the anterior cardiac nerve. These fine neurites arborize, producing numerous clusters of varicosities which are located within or just below the acn sheath. This image is a brightest pixel projection of 26 optical sections taken at 2.0 µm intervals. (B) A higher magnification view of a portion of the acn boxed in A. Note that many of the varicosities are connected together by fine neurites, giving rise to a `beads on a string'-like conformation. This image is a brightest pixel projection of 24 optical sections taken at 1.0 µm intervals. (C) A further magnified view of one cluster of FLRFamide containing varicosities boxed in B. Note the grape-like cluster of terminal varicosities. This image is a brightest pixel projection of 44 optical sections taken at 0.5 µm intervals. Scale bars, 100 µm (A,B); 25 µm (C).