ROLE OF THE RETE-MIRABILE-OPHTHALMICUM IN MAINTAINING THE BODY-TO-BRAIN TEMPERATURE DIFFERENCE IN PIGEONS

Brain (hypothalamic) and colonic temperatures were measured in twenty adult pigeons (Columba livia) whose mean body mass was 0.377 kg. In contrals, in sham operated birds, and in those pigeons in which one or both external ophthalmic arteries were occluded brain temperatures were always about 1°C (0.94 to 1.03) below body temperature (Fig. 2) over a range of air temperatures. In pigeons in which arterial flow to the retia was totally blocked, the normal pattern of body-to-brain temperature difference was reversed, such that brain temperature was always higher than body temperature by a mean of 0.36 °C (Fig. 2, Table 1). The rete mirabile ophthalmicum of pigeons plays a central role in the maintenance of the body-to-brain temperature difference which may be important in avoiding brain damage during core hyperthermia. © 1979, Springer-Verlag. All rights reserved.