Morphology of gill epithelia in fish

In fish of all groups examined including Teleostei, Chondrostei, Holostei, Chondrichytes, and Dipnoi, the primary epithelium that surrounds the primary lamellae has a close relationship with the venous compartment. Except in Dipnoi that displays a specialized epithelial drainage, the venous compartment consists of a central venous sinus that is connected with the systemic vasculature by noninnervated muscular arteriovenous anastomoses and …