1 In a medium-size bowl, combine the whole-wheat flour, oat bran, cornmeal, sugar, baking powder, baking soda, and salt. In a 1-pint glass measuring cup, combine the buttermilk, egg yolks, and oil.
2 In a perfectly clean large bowl, beat the egg whites with an electric mixer set on high speed until they form stiff peaks. Stir the buttermilk mixture into the flour mixture. Fold in the egg whites.
3 Lightly coat a 12-inch nonstick skillet with the cooking spray and set over moderate heat. When the skillet is hot, cook the pancakes 4 at a time, using 1/4 cup batter for each. Cook for about 2 minutes on one side or until bubbles appear on the surface; turn, then cook 2 minutes longer or until golden brown on each side and cooked through.