LONG-TERM SURVIVAL OF POSTEMBRYONICALLY BORN CELLS IN THE CEREBELLUM OF GYMNOTIFORM FISH, APTERONOTUS-LEPTORHYNCHUS

The gymnotiform fish Apteronotus leptorhynchus is, like all teleosts e xamined thus far, distinguished by its enormous potential for the prod uction of new neurons in the adult brain. In the cerebellum cells are generated continuously and at high rate in discrete proliferation zone s. From there, they migrate into specific target areas comprised of gr anule cell layers in the four cerebellar subdivisions. The longterm fa te of these cells was followed through labelling with 5-bromo-2'-deoxy uridine. Employment of survival times of up to 440 days after the admi nistration of this thymidine analogue revealed that the newborn cells survive for extremely long periods of time, spanning most of the fish' s adult life, without exhibiting a decline in their number. This long- term survival, together with the permanent addition of new cells to th e population of older cells, forms the basis for the continuous growth of the cerebellum during adulthood. (C) 1997 Elsevier Science Ireland Ltd.