Light- and electron-microscopic visualization of gamma-aminobutyric acid and GABA-transaminase in the oviduct of rats. Predominant occurrence in epithelium.

The distribution in the rat oviduct of gamma-aminobutyric acid and its catabolic enzyme GABA-transaminase was studied by the use of immunocytochemical and enzyme-histochemical techniques. At the light-microscopic level, both GABA immunoreactivity and GABA-transaminase enzyme reactivity were found primarily in the tubal epithelium while in the muscle layers of the organ only a faint GABA and GABA-transaminase positive staining could be detected. Electron-microscopic evaluation of the GABA immunoreactivity revealed a heavy labelling of the basal bodies (kinetosomes) and a moderate staining of the cilia. These findings indicate that the role of GABA in the oviduct is not related to neurotransmission but may be related to ciliary functions.