The provisions of this act do not apply to postmortem examinations performed under the authority of statutes pertaining to the coroner's office or the office of postmortem examinations. It shall be applicable in cases of the bodies of honorably discharged soldiers, sailors, marines or airmen of the United States or of the Militia of the State of Pennsylvania, or the bodies of women who have served the United States in military activities, if authorization for a postmortem examination is granted in accordance with this act. In such cases the bodies shall be buried in accordance with the provisions of existing Federal law. If no person is available who is entitled to authorize a postmortem examination on a veteran's body, the body shall not be subjected to postmortem study and shall be buried in accordance with the provisions of existing Federal law.