Morphology and Distribution of NADPH d Positive Tanycytes in the Ependyma of the Third Ventricle in Rat

In the present study, the ependymal tanycytes of the third ventricle in preoptic region (POR) of rat were investigated using NADPH diaphorase(NADPH d)histochemistry. It was found: 1) there existed the NADPH d positive tanycytes with their basal processes projecting to POR and contacting with neurons or capillaries; 2) the NADPH d positive tanycytes were frequently observed in the lateral walls of the third ventricle , but less commonly at the floor, and not found at the roof; 3) there was no significant sex differ ence in morphology and distribution of the NADPH d positive tanycytes. Although the physiological role of the NADPH d positive tanycytes is still poorly understood, the present investigation provides morphological evidence supporting that tanycyte may be a part of the brain cerebrospinal fluid circuit, serving important function of sensing chemical changes of cerebrospinal fluid (CSF), and that nitric oxide (NO) may contribute to this process.