Ultrastructural characterization of the extramammary Paget cell plasma membrane: a freeze-fracture study.

The plasma membrane ultrastructure of the extramammary Paget cells was characterized by freeze-fracture electron microscopy, which was first employed for the study of Paget cells. The Paget cell plasma membrane revealed a flat fractured plane with much fewer and smaller desmosome-particle aggregations than those of the keratinocyte. No gap junctions were detected. Many intramembranous particle-free vesicles were seen in the intercellular spaces. Particle-free blebs projecting from the plasma membranes were seen on some cell surfaces. These features greatly differed from those of keratinocytes. On the other hand, an increase of gap junctions was noticed o the keratinocytes around or in the Paget's disease lesions.