In the event a member, who has reciprocal service credit in force, retires under the public system on account of disability his annuity to be paid by the teacher system shall be subject to approval of his disability retirement by the retirement board of the teacher system. In the event a member, who has reciprocal service credit in force, retires under the teacher system on account of disability his annuity to be paid by the public system shall be subject to approval of his disability retirement by the board of trustees of the public system.