Such bonds and the coupons, if any, attached to such bonds, shall be executed in the name of the Medical University in such manner and by such persons as the trustees shall from time to time determine, and the seal of the Medical University shall be affixed to or impressed on each bond. Any coupons attached to such bonds shall be authenticated by the facsimile signature of one or more of the persons signing the bonds. The delivery of the bonds so executed shall be valid notwithstanding changes in officers or seal occurring after such execution.