Fig. 9. A schematic overview of the different receptors indicated in this study to be present in the gut at prometamorphosis, metamorphosis and juvenile stages. Most receptors seem to be directly situated on the smooth muscle. Plus sign indicates excitatory neuron, whereas minus sign indicates inhibitory neuron. Black receptors indicate excitatory effects while grey receptors indicate inhibitory effects. For possible receptor subtypes see discussion. M, muscarinic receptor; NK, neurokinin receptor. Other abbreviations as previously used in the text.