Rodent eccrine sweat glands: a case of multiple efferent innervation

The sweat territories of peripheral nerves to the hind-paw of the mouse were defined by a silastic impression mold method that allowed identification of every secreting sweat gland. It was found that the tibial, sural, saphenous and peroneal nerves all contribute to the innervation of foot pad sweat glands, and there is extensive overlapping of the sweat territories of the different peripheral nerves. Most sweat glands could be activated by electrical stimulation of axons in two or three peripheral nerves or in separate fascicles of one nerve. This was interpreted to indicate that these sweat glands receive multiple innervation and that sweat glands in the overlap regions between autonomous zones of adjacent cutaneous nerves can receive axons from each nerve. Partial denervation of sweat glands by section of one source of innervation did not prevent the gland from sweating during stimulation of intact axons to the gland, or after pilocarpine treatment. Totally denervated glands did not exhibit denervation hypersensitivity; they became unresponsive to pilocarpine, acetylcholine and adrenaline. These characteristics allowed detection of the appearance and progression of reinnervation (and reactivation) of denervated sweat glands by collateral branching from sudomotor fibers. Not only do these results increase our basic understanding of the anatomical relations between peripheral nerves and the sweat glands they innervate, but they also demonstrate that the mouse sweat gland provides a useful model system for studying neuropathology of the sympathetic nervous system.