1. The taenia of the guinea-pig caecum has been used as a model to study the re-establishment of autonomic innervation following
transplantation into the anterior eye chamber. The ultrastructure, the histochemical localization of
noradrenaline and
acetylcholinesterase and the pharmacology of transmission to the taenia have been examined 1 day to 16 weeks following
transplantation. Both
ganglion-free strips of the taenia and caecal wall segments including the underlying Auerbach's plexus were used.2. Caecal wall preparations: nerve fibres from intramural
ganglion cells retracted during the first 2 days following
transplantation, but reappeared in the muscle soon afterwards.
Adrenergic nerves from the iris formed terminals about
ganglion cells at about 2-4 weeks. Both
cholinergic excitatory and non-
adrenergic (;purinergic') inhibitory transmission to the muscle was re-established by 2-4 days following
transplantation.3. Taenia strip preparations: both
adrenergic and
cholinergic nerve fibres were demonstrated histochemically in muscle bundles by 2-4 weeks. Non-
adrenergic inhibitory and
cholinergic transmission was not re-established until 2-4 weeks following
transplantation. There was an abnormally dense re-innervation of the muscle by
adrenergic nerve fibres by about 8 weeks which is compared with the innervation of aganglionic bowel in
Hirschsprung's disease.4. The origin of non-
adrenergic inhibitory responses in the transplanted taenia is discussed and the results considered in relation to the re-innervation of transplants of the vas deferens and of intestine during early development.