Ultrastructural nuclear changes of extranucleolar ribonucleoprotein structures during autolysis of normal liver cells

The ultrastructural changes of extranucleolar nuclear ribonucleoprotein structures during autolysis of normal liver cells were studied by means of usual and cytochemical procedures. The results revealed that the earliest changes were characterized by the fragmentation of the perichromatin fibrils and disappearance of the perichromatin granules. This was followed by the formation of numerous dense granules among the altered perichromatin fibrils and by the disappearance of dense fibrillar structures from the remaining interchromatin areas. In the later stages of autolysis the altered perichromatin fibrils loosed their density and the dense granules located among them disappeared. In addition, fine filamentous and cross-striated bodies appeared in the nucleoplasm as well as in the cytoplasm of some hepatocytes. The results obtained by the EDTA treatment and digestion of the sections with Pronase and RNA-ase indicated that the altered perichromatin fibrils contained ribonucleoprotein which together with that of the perichromatin granules represent nuclear components most sensitive to the autolysis. The chemical nature of the dense granules located among the altered perichromatin fibrils was different from that of the latter as well as from that of the nuclear microspherules [6]. The dense fine filamentous and cross-striated nucleoplasmic and cytoplasmic bodies are considered to represent a nonspecific structural phenomenon accompanying regressive cellular alterations since these bodies were present only in the later stages of autolysis.