Advancement in the Examination of the Human Cardiac Sinus Node

• DOI: 10.1097/paf.0b013e3181ce9f23
• Publication Date: 2010-08-03T16:07:54Z
• Authors: Tiziana Balbi; Claudio Ghimenton; Gianandrea Pasqui...; Laura Foroni; Marco Grillini; Giovanni Pierini
• Keywords: Sinus (botany); Synaptophysin; Cell type; Matrix (chemical analysis); Transitional Cell

We have investigated the morphology of sinus node human cardiac conduction system. Until today (SN) is described as a heterogeneous system composed 2 types cells, namely, P or pale and T transitional cells which are immersed in matrix around nodal artery. said to share characteristics peripheral working atrial myocardial cells. This study was carried out on autoptic explanted specimens using histochemical, immunohistochemical, electron microscopic methods. Our investigations show that SN tissue has quite different cellular composition, ie, spherical and/or star-shaped organized clusters with long cytoplasmic processes (type P), similar myocytes but reduced number sarcomeres T) and, finally, yet not literature, fibroblast-like bi-tripolar extensions contacting Interestingly, squared by connective elastic fibers geometrically arranged. Immunohistochemistry shows 3 cell express mesenchymal markers revelatory their embryological origin. Innervation appears be more complex than previously thought; we identified synaptophysin-positive cholinergic vesicles dependent sympathetic parasympathetic expressing S100 protein. Overall results indicate an unexpected, systematic architecture.