Ornithine decarboxylase immunoreactivity in the pituitary gland. A comparative lightmicroscopical study

In the present study efforts are made to localize ornithine decarboxylase enzyme protein--the key enzyme of polyamine biosynthesis--in the adenohypophysis of different vertebrates by means of immunocytochemistry. The antigenic expression of ornithine decarboxylase was revealed in the pituitary of the clawed frog (Xenopus laevis D.), but not in rat and human adenohypophysis. The immunocytochemical results are compared with the staining pattern of the periodic acid-Schiff-reaction. No correlation between these results and the immunocytochemically obtained data has been found. Conclusions are drawn from the location of the enzyme and possible phylogenetic and humoral regulation mechanism.