Ultrastruct of the juxtaglomerular apparatus in the dog in a sodium-balanced state.
The ultrastructure of juxtaglomerular apparatuses (JGA) from four dogs in a state of sodium balance were examined. Plasma renin activity and urinary sodium excretion in the dogs were within normal values. At the vascular pole of the glomerulus, circumferentially oriented smooth muscle cells in the wall of the glomerular arteriole were abruptly replaced by modified smooth muscle cells with complicated interwoven cell processes. These modified cells were indistinguishable from the juxtaglomerular cells of the lacis region (extraglomerular mesangium). The basal lamina surrounding these modified smooth muscle cells in the wall of the glomerular arteriole was continuous with the basal lamina of the juxtaglomerular cells of the lacis (extraglomerular mesangium) and the macula densa. The most striking differences in the JGA of the dog, when compared with the JGA of other laboratory animals, are related to the observation that cytoplasmic secretory granules are less abundant in the dog, are generally smaller than the practical resolving capability of the light microscope, and are restricted to cells of the lacis area in the JGA.
D000818:Animals; D001160:Arterioles / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D004285:Dogs / Q000033:anatomy & histology* / Q000378:metabolism; D007606:Juxtaglomerular Apparatus / Q000098:blood supply / Q000648:ultrastructure*; D008297:Male; D009130:Muscle, Smooth / Q000648:ultrastructure; D012083:Renin / Q000097:blood; D012964:Sodium / Q000378:metabolism* / Q000652:urine
D012964:Sodium; D012083:Renin