Scanning Electron Microscopy


The gill vasculature of euryhaline striped bass, Morone saxatilis, was examined by scanning electron microscopy of corrosion casts prepared by injecting resin (either Mercox/Sevriton or L.R. White) into the ventral aorta. The vasculature of the striped bass gill appears to be similar to that of other euryhaline species. The striped bass gill has three major vascular systems: (1) a respiratory system, (2) an arterio-venous system, and (3) a nutritive system. In the respiratory system, blood from the afferent branchial artery flows to each filament via an afferent filamental artery, and from there to the highly vascularized respiratory lamellae. Lamellar blood is conducted back to the efferent branchial artery via the efferent filamental artery. In the second system arterio-venous anastomoses transport blood from the efferent filamental artery to the central venous sinus. Blood then flows to the branchial vein either directly or via paired afferent companion vessels. No arterio-venous anastomoses connecting the prelamellar vessels with the central venous sinus have been found. Finally, nutritive branches to the arch are provided by the efferent branchial artery and the efferent filamental artery. The striped bass does not have a lamellar bypass system involving the central venous sinus as reported in other species. Intralamellar distribution mechanisms and lamellar recruitment may account for changes in respiratory lamellar perfusion during decreased and increased oxygen demand, respectively. The central venous sinus' role may be partially nutritional since its blood is oxygenated. However, its complex vascular connections may permit a variety of other functions.

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