Arteriovenous anastomoses in the afferent region of trout gill filaments (Salmo gairdneri richardson,teleostei)

Summary Arteriovenous anastomoses (AVAs) in the afferent region of trout gill filaments originate from two small filament arteries (Fromm's arteries), which parallel the main afferent filament vessel on either side. As in the efferent filament arteries the origin of AVAs is bordered by specialized endothelial cells. Fromm's arteries originate from efferent filament or branchial arteries. A few extremely narrow connections between the afferent filament artery and Fromm's arteries (= afferent shunts) do exist in some gill filaments. Nevertheless, the AVAs in the afferent filament region carry mainly arterialized blood, or blood plasma, to the central venous sinus of the filament.Supported by the Deutsche Forschungsgemeinschaft (Vo 229/1)