Nucleolar changes in aging and autogamous Paramecium tetraurelia.
A significant loss in nucleolar volume density (proportion of nuclear volume occupied by nucleoli) occurs in the macronucleus as clonal age increases, which suggests an age-correlated loss of ribosomal RNA synthesizing capacity. In the macronuclear fragments of cells undergoing autogamy, however, a significant gain in nucleolar volume density takes place.
D000375:Aging; D000818:Animals; D002466:Cell Nucleolus / Q000648:ultrastructure*; D008854:Microscopy, Electron; D010247:Paramecium / Q000648:ultrastructure*; D012100:Reproduction, Asexual; D014617:Vacuoles / Q000648:ultrastructure