RESUMEN
The present work studies the atrioventricular (AV) junctional area in 15 hearts of P. cynocephalus perfused with phosphate-buffered formal 10%; 12 hearts were studied by gross anatomy and mesoscopic dissection, 3 hearts were serial sectioned in frontal plane (10 micron) and stained by trichromic method. The results show that the junctional AV area in P. cynocephalus is approximately similar to the same region in M. fascicularis and also in the human heart (Mandarim-de-Lacerda et Penteado in press, Mandarim-de-Lacerda et Hureau in press). It was impossible to dissect the AV node and AV bundle while the left bundle branch was easily identified as a calibrous fan-like fashion on the left side of the interventricular septum. The right bundle branch left the AV bundle and penetrated the myocardium of the trabecula septo-marginalis (moderator band).