CYTOCHEMICAL AND IMMUNOCYTOCHEMICAL CHARACTERIZATION OF NUCLEAR-BODIES DURING HIBERNATION

Brown adipose tissue and liver of hibernating, arousing and euthermic individuals of the dormouse Muscardinus avellanarius were studies usin g ultrastructural cytochemistry and immunocytochemistry with the aim t o investigate possible fine structural modifications of the cell nucle us during the seasonal cycle. The general morphology of brown adipocyt e and hepatocyte nuclei was similar in the three experimental groups. However, three nuclear structural constituents were identified only in hibernating individuals: coiled bodies (CBs) and amorphous bodies (AB s) were observed in hepatocytes and, together with bundles of nucleopl asmic fibrils (NF), were present in brown adipocytes of hibernating do rmice. In arousing animals only some structural constituents suggestiv e of poorly structured CBs were found. The latter showed the same immu nocytochemical features as CBs of hibernating individuals, suggesting that they are disappearing CBs. A possible involvement of CBs in stori ng and/or processing RNA which must be rapidly and abundantly released upon arousal is discussed. ABs similarly to CBs contain RNA and nucle oplasmic ribonucleoproteins (RNPs) and could also be involved in mRNA pathways. NF do not contain nucleic acids or RNPs and seem to be compo sed of proteinaceous material; their functional role in the nuclear me tabolism of hibernating brown adipocytes remains unclear.