A comparative study on the secretory activity of the subcommissural organ in the European green frogs: Rana esculenta, rana lessonae and Rana ridibunda

Abstract

Abstract-l. The subcommissural organ (SCO), present in all vertebrates, is situated in the roof of the third brain ventricle, and secretes into this ventricle a glycoproteinaceous, fibre-like structure, the liquor fibre (LF).2. The three forms of European green frogs differ from each other in the three parameters used to measure the secretory activity of the SCO: the amounts within the SC0 of stained secretory material and of secretory material labelled by a radioactive precursor, and the growth rate of LF.3. The observed differences indicate that the secretory activity of the SC0 is distinctly higher in Rana ridibunda than in Ram lessonae, whereas in Ram esculenta this activity is intermediate.