Immunohistochemical Characterization of Sympathetic Chain Ganglia (SChG) Neurons Supplying the Porcine mammary Gland

The aim of this study was to investigate the chemical coding of mammary gland-projecting SChG neurons using double-labelling immunohistochemistry. Earlier observation showed that after injection of the retrograde tracer fast blue (FB) into the second, right thoracic mamma, FB+ mammary gland-projecting neurons were found in Th1-3, Th9-14 and L1-4 right SChG. The greatest number of FB+ nerve cell bodies was observed in Th10 (approx. 843) and Th11 (approx. 567). Neurons projecting to the last right abdominal mamma were found in L1-4 SChG. The greatest number of FB+ neurons was observed in L2 (approx. 1200). Immunohistochemistry revealed that the vast majority of FB+ mammary-projecting neurons contained immunoreactivities to TH (96.97%) and/or D beta H (95.92%). Many TH/D beta H-positive neurons stained for SOM (41.5%) or NPY (33.2%), and less numerous nerve cells expressed VIP (16.9%). This observation strongly corresponds to the results of previous studies concerning the immunohistochemical characterization of nerve fibres supplying the porcine mammary gland.