PARVALBUMIN IMMUNOREACTIVITY DURING THE DEVELOPMENT OF THE CEREBELLUMOF THE RAINBOW-TROUT

The distribution of parvalbumin immunoreactivity in the developing cer ebellum of the rainbow trout was studied by using a specific monoclona l antibody and the avidin-biotin peroxidase method. Parvalbumin immuno reactivity was absent during the embryonic development of the cerebell um. The first immunoreactive elements, identified by their localizatio n and posterior morphological evolution as immature Purkinje cells, ap peared at 6 days posthatching in the presumptive corpus cerebelli and lobus vestibulolateralis. The labeling extended throughout the cerebel lum following a caudorostral gradient, and in 21 days alevins, parvalb umin immunoreactive Purkinje cells were also observed in the valvula c erebelli. The appearance of parvalbumin-immunostaining in the Purkinje cells was not simultaneous; the labeling was observed initially in th e cell body, extending gradually to the dendritic branches and finally to the axon. From 1 year onwards, parvalbumin immunoreactive terminal puncta from the Purkinje cell axons were observed surrounding the cel l bodies of eurydendroid cells, that were parvalbumin immunonegative i n all developmental stages studied. The spatio-temporal pattern of par valbumin immunoreactivity in the rainbow trout cerebellum is different to previous observations in the cerebellum of amniotes. (C) 1998 Else vier Science B.V. All rights reserved.