Functional differences between dorsal and ventral hippocampus revealed with AgNOR staining

Recently differences were reported concerning the dorsal and ventral zones of hippocampal formation. These differences may play an important role rega rding the differential involvement of both zones in learning and memory. We use here the silver staining of nucleolar organizer regions (AgNORs) histo logical technique in order to analyze the biosynthetic activity of CA1 and CA3 hippocampal areas in dorsal and ventral zones from Wister rats. We quan tified the mean number and area of AgNORs in their neurons, which are consi dered as indirect indexes of protein synthesis activity. The results show a significantly higher biosynthetic activity in the dorsal region from the a reas studied, which agrees with previous research. Functional implications derived from our results are discussed in this paper.