Differences in the structure of the rete ophthalmicum among three breeds of domestic fowls,Gallus gallus f. domesticus (Aves)

Summary The morphology of the rete ophthalmicum, which functions as a brain cooling system, was studied in the desert-origin Bedouin fowl in comparison with two commercial breeds: the White Leghorn and the White Plymouth Rock.Cross-sections of the rete ophthalmicum revealed a significantly higher degree of arteriovenous contact in the Bedouin fowl than in the commercial breeds (P<0.01). Based on the allometric relationship between the heat exchange area in the rete and body weight, the Bedouin fowl has a significantly higher heat exchange area than non-Bedouin fowls of similar body weights (P<0.02).These findings suggest that the higher heat exchange area and the high degree of arteriovenous contact in the rete ophthalmicum of the Bedouin fowl is an adaptation to desert conditions, and contributes functionally to the apparently superior heat resistance in this desert breed.