Light- and electron-microscope studies on the pseudobranch of the golden orfe, Leuciscus idus L.

The structure of the pseudobranch of the golden orfe is described from light- and electron-microscopical observations. It is characterized as a covered pseudobranch overlaid by a mucous membrane. The pseudobranch of the golden orfe has no respiratory function, but the electronmicroscopical results indicate that it could function endocrinally by registering and regulating salinity or osmolarity. The epithelial cells are represented by pseudobranch-type cells. No chloride cells were seen. Rodlet cells are located near blood vessels at the base of the pseudobranch and in the covering epithelial layer, together with mucous cells and mast cells. In the endothelial intima of the arteries the so-called Weibel-Palade bodies are described.