DISTRIBUTION OF THE NUMBER OF ARGYROPHILIC NUCLEOLAR ORGANIZER REGIONS IN A STUDY OF POSTNATAL-DEVELOPMENT AND AGING IN THE RAT HIPPOCAMPUS

We applied the silver staining technique to nucleolar organiser region s (NORs) in a study of postnatal development (14P, 21P and 90P) and ag eing (22 months) of hippocampal areas CA1 and CA3 in the rat. Both are as play a differential role in the functions of the hippocampus in the rat. The percentage distribution of the number of Ag-NORs (argyrophil ic nucleolar organiser regions) is used to assess neuronal biosyntheti c activity in these regions, and previous studies have related this pa rameter to cellular transcriptional activity. Our results reveal a dif ferent Ag-NOR distribution in areas CAT and CA3 only in adult animals. This difference becomes less pronounced in older rats. These findings are discussed in the context of clinical data related to differential effects of development and ageing on the hippocampus.