MORPHOLOGICAL AND MORPHOMETRIC CHANGES IN MESOTHELIAL CELLS DURING PERITONEAL-DIALYSIS IN THE RABBIT

The morphometric and morphological changes in the mesothelial cell pop ulation were studied in rabbits in peritoneal dialysis with lactate an d bicarbonate buffer solution. During dialysis the mesothelial populat ion underwent radical changes in morphology and morphometric analysis showed a significant increase in cell size. Light microscope examinati on showed two types of changes: hyperplasia of the mesothelial cell wi th diameters of up to 80 mu m, nucleus proportional to the cytoplasm, a large nucleole giving an owl's eye appearance and cytoplasm rich in granular material. The second change was multiple nuclei and arrest of cell division. Nuclear division occurred, but no separation of the cy toplasm. The cells became larger than 200 mu m, packed with nuclei and relatively little cytoplasm. Electron microscopy confirmed that the h yperplastic cells had perfect structure whereas the polynucleate cells contained vacuoles and little cytoplasmic reticulum. Immunohistochemi stry using monoclonal antibodies SK2-27 and SK 60-61 specific to cytok eratins 14, 16, 17 and 8, 18, respectively, identified the cells as me sothelial. The changes were related to the glucose content of the peri toneal dialysis solution. Glucose is therefore the bioincompatible age nt that modifies the mesothelium during peritoneal dialysis, causing i t to become hyperplastic or blocking replication.