Preheat oven to 400°. Lightly grease baking sheet(s); set aside. In a small bowl, combine chicken, celery, onions, 1/2 cup cheese and salad dressing. On a lightly floured surface, divide each loaf into 4 equal pieces. Roll each dough piece into a 4×6″ rectangle. Spoon 3-4 tablespoons of chicken mixture on each piece of dough, along the 6-inch side. Roll up tightly, in jellyroll fashion. Seal seams. Brush with melted butter or vegetable oil. Sprinkle lightly with remaining cheese. Bake immediately for 15-20 minutes. Remove from oven. Brush with additional butter or oil. Serve warm.