[The effect of low ionic strength solutions on the structure and function of the nucleoli in living ESK cells]

The effect of a 20% Hanks [correction of Hanx] solution on living cells of pig embryo kidney culture induces sharp changes in the structural and functional organization of nucleoli. 10-15 min after the beginning of the effect, no nucleoli are observed under the light microscope. The ultrathin sections reveal only fibrillar centers (FC) and a dense fibrillar component. Under these conditions nucleoli do not incorporate 3H-uridine. However, 30-120 min after the cells are transferred from the hypotonic to the normal isotonic medium, the nucleoli cannot be distinguished from initial ones by their form, size, location in the nucleus, ultrastructure and the 3H-uridine labelling pattern. This indicates that the effect of a 20% Hanks [correction of Hanx] solution on nucleoli of living PE cells is reversible. It has been suggested that reconstruction of nucleoli in the full culture medium may proceed at the expense of both synthesis de novo and the material of initial nucleoli.