The innervation of the renal cortex in the dog. An ultrastructural study

Two cytochemical techniques were used at the ultrastructural level to study the distribution of specific axon types to different intrarenal structures in the dog. Using the chromaffin reaction to distinguish catecholaminergic fibres from other axon populations, it was found that the renal cortex of the dog is supplied only by catecholaminergic nerves. Immunostaining for tyrosine hydroxylase (TH) labelled all of the intracortical nerves, and 20% to 25% of these profiles also contained dopa decarboxylase (DDC)-immunoreactivity, indicating they were dopaminergic rather than noradrenergic. Both DDC-positive and DDC-negative axons were seen in close association (approximately 80 nm) with blood vessels and juxtaglomerular cells as well as tubular epithelial cells. The distribution of TH- and DDC-immunoreactive nerves in the renal cortex is compatible with existing functional evidence indicating that both dopaminergic and noradrenergic nerves are involved in the regulation of renal blood flow, tubular reabsorption and renin release.