Localization of intra-abdominal thermoreceptors in the ewe

1. In neutral environmental temperatures, shivering was induced in sheep by intra-ruminal cooling. Shivering was then depressed for a period by intra-abdominal heating. Intra-abdominal heating without ruminal cooling induced panting and a reduction of caval temperatures. Posterior caval temperatures were found to be inappropriate to the responses observed.2. Intra-abdominal heating of sheep in cold and warm environments depressed shivering and augmented panting respectively. Unilateral splanchnotomy abolished these responses on the ipsilateral side.3. The results are interpreted to indicate that the thermoreceptors stimulated lie within the walls of the rumen and intestine, and possibly the mesenteric veins.4. The splanchnic nerves are indicated as the afferent pathway for these receptors, and differential splanchnic innervation of the gut is suggested to explain unilateral abolition of the response to warming.