The regeneration of adrenergic nerves in a free microvascular groin flap in the rat.

The regeneration of adrenergic nerves in free microvascular groin flaps in the rat was investigated. The adrenergic nerves were revealed with glyoxylic acid-induced fluorescence and with formaldehyde-induced fluorescence methods. In the control specimens taken from the contralateral groin, adrenergic nerves were seen in the erector pili muscles and as networks around arteries and arterioles. In the free flap four weeks postoperatively, a few regenerating adrenergic nerves were observed at the margins under the flap and following the pedicle. Eight weeks postoperatively many tiny regenerating nerves were observed to invade the flap at the margins and under it. Many regenerating nerves were observed to reinnervate the artery and vein, forming a nerve plexus in the pedicle. The number of single nerve fibres invading the flap at the margins decreased sixteen weeks postoperatively, but more nerves were observed along arterioles in the flap and pedicle. Twenty-four weeks postoperatively some regenerating adrenergic nerves were observed around arteries and arterioles in different areas in the flap and in erector pili muscles. A rich network of nerves remained around the pedicle. However, the reinnervation of the vasculature of the flap remained patchy and inadequate, and many arteries and arterioles remained without innervation.