[A histo-cytological contribution to the knowledge of atrial internodal connections (author's transl)].

The problems, still widely discussed, concerning the demonstration of specific internodal conducting pathways in the right atrium have been reviewed, in the light of histo-cytological findings on the initial tracts of Bachmann's (anterior) and Thorel's (posterior) bundles in 7 human hearts. The evidence of Purkinjan cells and of small myocytes, together with the richness in connective tissue and nervous component, make these tracts clearly distinguishable from the common myocardium and seem to substantiate the thesis of morphologically discrete internodal connections.