OCCURRENCE OF MELANOSOME-CONTAINING MERKEL CELLS IN MAMMALIAN ORAL-MUCOSA

The occurrence and fine structure of Merkel cells with melanosomes in the labial epithelium of the dog and cat were studied by electron micr oscopy. These melanosomes were polarized in the Merkel cell cytoplasm opposite to the major aggregation ot dense-cored granules and the clos ely abutting nerve terminal. None of melanosomes was found in the Golg i complex region where a few immature dense-cored granules were observ ed. This may suggest that the melanosomes are not produced in the Merk el cell, but are taken from the melanocytes like in keratinocytes. The possible phagocytotic ability of Merkel cells is discussed.