805 ILCS 10/10
A professional corporation organized under this Act shall be governed by a board of directors elected by the shareholders and represented by officers elected by the board of directors, and, if desired, by an executive committee elected by the board of directors. If such corporation has only one shareholder it need have only one director who shall be such shareholder and may also serve as president, secretary, and treasurer of the corporation. Such one shareholder corporations need not have a vice-president. If such corporation has only 2 shareholders it need have only 2 directors who shall be such shareholders and they shall fill the offices of president, vice-president, secretary and treasurer of the corporation between them.
805 ILCS 10/10