The bonds shall be signed by the presiding officer of the board and countersigned by the clerk or secretary of the local taxing entity, and the coupons shall be signed by the clerk or secretary. All signatures except that of the clerk or secretary on the bonds may be printed, lithographed or engraved. If any officer whose signature appears on the bonds or coupons ceases to be such officer before the delivery of the bonds, his signature is as effective as if he had remained in office.