The ribosome cycle,nucleoli, and cytoplasmic nucleoloids in the meiocytes ofLilium

Summary During the meiotic prophase in pollen mother cells ofLilium species the ribosome population of the cytoplasm diminishes to a minimum reached during the diplotene-diakinesis interval. This fall is associated with a drop in the ribonuclease-extractable RNA present in whole, fixed cells. A rise in RNA and in number of observable ribosomes follows during the meiotic mitoses and in the very early life of the spores. Bodies with the characteristics of nucleoli—here termed nucleoloids—are released into the cytoplasm at anaphase I and anaphase II, and it is suggested that these may represent the main mechanism through which the ribosome population of the cytoplasm is restored after the prophase elimination.