Mich. Comp. Laws § 450.1331: Share certificates.

Sec. 331.

Except as provided in section 336, the shares of a corporation shall be represented by certificates which shall be signed by the chairperson of the board, vice-chairperson of the board, president or a vice-president and which also may be signed by another officer of the corporation. The certificate may be sealed with the seal of the corporation or a facsimile of the seal. The signatures of the officers may be facsimiles. If an officer who has signed or whose facsimile signature has been placed upon a certificate ceases to be an officer before the certificate is issued, it may be issued by the corporation with the same effect as if he or she were the officer at the date of issue.