Vacuoles in the Nucleoli of Zea Mays Root Apices and their Possible Significance in Nucleolar Physiology

SUMMARY

Nucleolar vacuoles in eight regions of the root apex of Zea mays have been studied. The volume of the vacuoles ranges from about 1 μm³ to 0.001 μm³ with a mode value between 0.075 and 0.01 μm³. The number of vacuoles within a nucleolus ranges from 0–20 and is correlated with nucleolar volume. In all regions studied the average volume of the nucleolus occupied by vacuoles is about 3 percent. It is suggested that the metabolic capacity of the nucleolus may be reflected in the rate of formation of the vacuoles and the discharge of their contents to the cell.