The Surface Morphology of the Cat Subfornical Organ
As one of the circumventricular organs, the subfornical organ (SFO) is present in all mammalian and other vertebrate species. Several studies on the ultrastructure of the SFO, as revealed by scanning (SEM) and transmission electron microscopy (TEM), have been carried out (for a review see 1). The fact that this highly vascular organ has intimate contact with the cerebrospinal fluid (CSF) and that it is located outside the blood-brain barrier has led to the hypothesis that this structure is involved in the monitoring of the contents of the CSF and in neurosecretion. The results of recent studies have indicated that the SFO may contain receptors for the octapeptide angiotensin II which are neuronally linked to a drinking circuit. When injected into the ventricles of unanesthetized animals, angiotensin induces thirst (2). Furthermore, neurones in the SFO can be activated by angiotensin ejected microiontophoretically as well as by intravenous injection and direct application on to the surface (3). Since these studies have shown the existence of blood-borne receptors and receptors on the ventricular side, the surface morphology of the SFO is of particular interest.
KeywordsEpendymal Cell Intermediate Zone Circumventricular Organ Transmission Electron Microscopy Section Subfornical Organ
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- 1.H.-D. Dellmann and J. B. Simpson, The subfornical organ, Int.Rev. Cytol. 58: 333 (1979).Google Scholar