[Oncocytes in a mixed canine mammary gland tumour].

The electronmicroscopic findings of a canine mixed mammary gland tumour containing oncocytes, are described. The tumour consists of small myxoid foci and glandular formations with an organoid structure. The glandular walls are composed of myoepithelial differentiated cells and epithelial cells. Most of the latter are oncocytes and characterized by an extensive amount of pathic mitochondria. The myxoid foci consist of myoepithelial differentiated cells.