[Seasonal changes in the adrenergic fibers in the wall of the microvessels of the cheek pouch of the hamster, Mesocricetus auratus].

Adrenergic innervation has been investigated by fluorescent histochemical method with glyoxylic acid. Adrenergic fibers were found in summer period on the arterioles with a diameter varying from 100 to 30 micron, their fluorescence being significantly lower than that in the vessels of microcirculatory bed of the mesentery, tongue, femoral muscles of the same animal. No adrenergic fibers were revealed on the arterioles with a smaller diameter, on veins and venules. In winter period, fluorescence is completely absent from all the vessels of the cheek pouch, which may be due to the decrease in the level of catecholamines in the nerves and other tissues during hibernation.