Non-random distribution of fluorescing chromatin bodies resembling Y chromatin was observed among the cell populations of various organs obtained by autopsy of 52 adults. This type of Y-chromatin-like fluorescence is more frequent in thyroid and brain than in other organs. The Y-chromatin-like bodies of thyroid nuclei are not closely correlated with the brilliantly fluorescing autosomal blocks of lymphocyte mitoses of the same persons, as it was demonstrated in surgical cases.