(a) When an employee who has withdrawn from service reenters service before age 65, any annuity previously granted and any annuity fixed for his wife shall be cancelled. The employee shall be credited for annuity purposes with sums sufficient to provide annuities equal to those cancelled as of their ages on the date of re-entry; provided, the maximum age of the wife for this purpose shall be as provided in Section 11-150 of this Article.
     The sums so credited shall provide for annuities to be fixed and granted in the future. Contributions by the employee and by the city for purposes of this Article shall be made, and when the proper time arrives, as provided in this Article, new annuities based upon the total sum accumulated to his credit for annuity purposes and the entire term of service shall be fixed for the employee and his wife. If the employee’s wife is not his wife when he re-enters service, no part of any credits for widow’s annuity or widow’s prior service annuity at the time annuity for his wife was fixed shall be credited upon re-entry into service, and no such sums shall thereafter be used to provide such annuity.
     (b) When an employee re-enters service after age 65, payments on account of any annuity previously granted shall be suspended during the time thereafter that he is in service, and when he again withdraws, annuity payments shall be resumed. If the employee dies in service, his widow shall receive the amount of annuity previously fixed for her.