Purkinje cells were isolated from both ventricles of young adult domestic pigs and examined by transmitted light or laser scanning confocal microscopy. Purkinje cells in free running Purkinje fibres were organised in multicellular strands where individual cells were tightly connected end-to-end and closely side-to-side. After isolation, single cells gradually lost the elongated appearance and became more rounded, but the cell membrane remained smooth and undamaged. The contractile material was not very dense and was seen most clearly in the submembraneous area. Staining of the cell membrane with the lipophilic fluorescent (lye di-8-ANNEPS, and visualization with confocal microscopy, confirmed that the cell surface membrane was smooth without blebs. This staining also showed that Purkinje cells had no transversal tubules. We reconstructed the three-dimensional geometry of the Purkinje cells and determined the cell size. The average values were 62 +/- 9 microm for length, 32 +/- 3 microm for width, and 41 +/- 4 microm for depth (n = 7). Calculated cross-section area and volume were 1047 +/- 167 microm2 and 47 +/- 14 pl. Compared to ventricular cells, the morphology of the Purkinje cells reflects their specific role in impulse conduction.