Each stock certificate shall be signed by the president, a vice president, the chief executive officer, the chief operating officer, the chief financial officer, the chairman of the board, or the vice chairman of the board and countersigned by the secretary, an assistant secretary, the treasurer, an assistant treasurer, or any other officer. Each certificate which represents any stock, bond, note, guaranty, obligation, or other corporate security: May be sealed with the actual corporate seal or a facsimile of it or in any other form; and The signatures may be either manual or facsimile signatures. A certificate described in this section is valid and may be issued whether or not an officer who signed it is still an officer when it is issued.