LOCALIZATION OF SYMPATHETIC POSTGANGLIONIC NEURONS INNERVATING THE FEMORAL-SAPHENOUS VEIN IN CATS

Physiological and histochemical studies have suggested that the limb v eins are innervated by sympathetic adrenergic fibers. In the present e xperiment, horseradish peroxidase (HRP) was used as a retrograde trace r to identify and localize the sympathetic postganglionic neurons that innervate the femoral-saphenous vein in cats. In anesthetized cats, H RP was applied perivascularly on a femoral and a saphenous vein segmen t (4-8 mm in length for each segment) to allow uptake into the nerve e ndings. The sympathetic chains on both sides were dissected after the animal was sacrificed and fixed 60 h following the HRP application. Hi stological examination on serial section was done to count the HRP-lab eled neurons in each sympathetic ganglion from L1 to S1. In 10 cats, t he total number of HRP neurons amounted to 8569. Most neurons arose fr om L3 (47%) and then L4 (31%). The number of neurons became progressiv ely decreasing towards both ends of the sympathetic chain. Few neurons (less than 2% of the total) were discovered in the contralateral symp athetic ganglia. In each ganglion, the distribution of HRP neurons app eared to be scattering. Our findings provide anatomical evidence to su pport that the femoral-saphenous vein of the cat was innervated by the sympathetic efferent fibers. The main origins of these neurons are th e third and fourth lumbar sympathetic ganglia.