IMMUNOHISTOCHEMICAL DEMONSTRATION OF L-ORNITHINE DECARBOXYLASE ENZYMEPROTEIN IN DIFFERENT AREAS OF THE DEVELOPING HUMAN BRAIN

L-Ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis and thus a unique marker of the proliferation and matura tion processes, has been localized by means of immunohistochemistry in the human central nervous system. The enzyme protein has not only bee n found in the developing nervous system but also in the adult brain. The first immunopositive neuroblasts occurred in the 15th week of grav idity, whereas an increasing number of structures in the medulla oblon gata and cerebellum showed ODC immunoreactivity in weeks 18-24 of grav idity. ODC immunoreactivity was revealed in multiple neurons and in th e ependymal lining of ventricles. In the adult human brain ODC immunor eactivity was found in the hippocampus and in the spinal cord. In no c ase were immunoreactive glial cells observed.