CHANGE IN SIZE, NUMBER AND MORPHOLOGY OF THE NUCLEOLI IN HUMAN HEARTSAS A RESULT OF HYPERFUNCTION

In the present study we examined light-microscopically the nuclei of 1 6 hearts (7 normal hearts, 7 hearts with hypertrophy and 2 hearts with atrophy) for the size, number and morphology of their nucleoli. The s ize of the nucleoli, defined as the total area of all nucleoli per nuc leus, was an early and sensitive indication of a beginning hypertrophy of the myocardium. It increased in parallel to the total heart weight and to the total area of the nucleus of the cell, but initially the s ize of the nucleoli changed earlier than the other parameters. We foun d an increase of the ratio in the total area of the nucleoli per nucle us to the total area of the nucleus at the beginning of clinical hyper function. This ratio normalised during chronic hyperfunction. The numb er of the nucleoli also increased during hyperfunction, but it did not exceed the number of nucleolus organiser regions (NOR) given by the n umber of chromosomes. Nevertheless, we found numbers of nucleoli highe r than 10 because the number of NORs increases during polyploidization . Regarding the morphology of the nucleoli in hearts with hypertrophy, we found a predomination of the nucleoli with a highly branched nucle olonemal structure as an indication of an increased RNA synthesis.