The juxtaglomerular apparatus (JGA) in the rabbit kidney was examined by transmission electron microscopy and by freeze fracturing. It was found, that the Goormaghtigh cells of the JGA are extensively coupled with the mesangial cells within the glomerular tuft by gap junctions. A broad band of gap junctions starting within the Goormaghtigh cells, traversing the transitional area at the root of the glomerular tuft and continuing along the mesangial cells has been revealed by freeze fracturing. No gap Junctional connections to the macula densa cells have been found. In accordance with data from literature it may be stated that all smooth muscle derived cell groups at the vascular pole of the glomerulus (smooth muscle cells of the vas afferens and efferens, granular cells, Goormaghtigh cells, mesangial cells) are extensively coupled by gap junctions with each other. It is supposed that this cell system may act as a synchronized functional unit.