Parvalbumin immunoreactivity in the telencephalic hemispheres of the tench, Tinca tinca.

The distribution of parvalbumin immunoreactivity in the telencephalic hemispheres of the tench (Tinca tinca L.) was studied using a monoclonal antibody and the avidin-biotin immunoperoxidase method. A wide distribution of immunoreactive structures was found in both dorsal and ventral areas of the telencephalic hemispheres. Normally, the parvalbumin-immunostained neurons in the dorsal area were smaller, more weakly stained, and more scattered than those in the ventral one. In the dorsal area, parvalbumin-immunoreactivity was observed in practically all divisions. The highest density of positive somata was found in the lateral nucleus. Density of stained fibres was generally low. Labelling in the ventral area appeared in the ventral and dorsal nuclei, with a high density of both immunoreactive fibres and cell bodies. Neurons were seen close to the ventricle, arranged in two groups of neurons with different sizes and morphologies. The distribution and morphological characteristics of the parvalbuminergic cells were similar to those of previously described GABAergic elements, suggesting a possible colocalization of both substances in the teleost telencephalon, as it has been observed in different telencephalic areas of land vertebrates. On the other hand, significant differences were seen between the distribution of parvalbumin in the telencephalic hemispheres of the tench in comparison with its distribution pattern in supposed homologous structures of the forebrain of amniotes.