Del. Code tit. 8 § 610
No professional corporation may issue any of its capital stock to anyone other than an individual who is duly licensed or otherwise legally authorized to render the same specific professional service or any of the component qualified related professional services as those for which the professional corporation was organized. No shareholder of a professional corporation shall enter into a voting trust agreement, proxy, or any other type of agreement vesting another person with the authority to exercise the voting power of any or all of such shareholder's stock, unless such other person is also a shareholder of the professional corporation duly licensed or otherwise legally authorized to render the same specific professional service as such shareholder. Subject to the professional corporation's certificate of incorporation, the estate of a shareholder who was a person duly licensed or otherwise legally authorized to render the same professional service or any of the qualified related professional services as that for which the professional corporation is organized may continue to hold stock pursuant to the certificate of incorporation for a reasonable period of administration of the estate, but shall not be authorized to participate in any decisions concerning the rendering of professional service.
8 Del. C. § 610