Cellule PCNA positive nel cervelletto di un Teleosteo adulto,Carassius carassius L.

Abstract

Among heterothermic Vertebrates, only Teleosts have a cerebellum with elements that conserve embryonic characters into adulthood; such cells are present in other encephalic regions but are more abundant in the cerebellum. This is due to the presence in Teleosts of generalized tissue proliferation that does not cease when the organism reaches full body size, a phenomenon reflected in proliferation and/or maturation events that influence the plasticity of the nervous tissue and thus the brain. Kirsche (1967) reported the persistence in the adult Teleost cerebellum of cells with characteristics similar to those of neuroblasts. In subsequent decades, the expression of spontaneous proliferation was studied in juvenile and/or adult Teleosts, first with histological methods (especially autoradiography after inoculation with3H-thymidine) and then with immunocytochemical methods. Recently, we employed a current immunocytochemical test based on Proliferating Cell Nuclear Antigen (PCNA), a reliable marker for thein situ detection of cells in the S phase, to investigate normal proliferation first in the telencephalon and then in the mesencephalon in adults ofCarassius carassius. In the present study, the immunocytochemical expression of PCNA, indicating spontaneous mitotic activity, was detected in different degrees in the main cerebellar components (valvula cerebelli, corpus cerebelli, eminentiae granulares). Cells showing DNA synthesis were distributed in both the molecular and granular layers. As found previously for the telencephalon and mesencephalon, our results are virtually identical to those reported in the literature; the smaller amount of PCNA immunoreactivity can perhaps be attributed to the age of our specimens.