The use of periodic acid-thiocarbohydrazide-silver protein-physical development (PA-TCH-SP-PD) procedure for the histochemical detection of neutral carbohydrates in the circumventricular organs of the rat.

A periodic acid-thiocarbohydrazide-silver protein-physical development (PA-TCH-SP-PD) procedure was applied to the rat circumventricular organs (CVOs), which are known to be specialized structures in the brain. In the rat CVOs, vivid PA-TCH-SP-PD reactions were obtained in the apical surface and cytoplasm of the ependymal cells of the subcommissural organ (SCO) and the epithelial cells in the choroid plexuses (CPs) examined, and similar positive reactions were detected in the vascular walls and perivascular connective tissues in all the CVOs tested. Further, varying intensities of PA-TCH-SP-PD reactions were noted in the neuronal and glial networks of the organum vasculosum laminae terminalis (OVLT), subfornical organ (SFO) and area postrema (AP). The results obtained in the present study indicate that in the rat CVOs the histologic structures mentioned contain varying amounts of neutral carbohydrates and possible histophysiological significances of these carbohydrates in these organs have been discussed with references to their functions.