There is a Medical Service Corps in the Army. The Medical Service Corps consists of—

((1)) the Chief of the Medical Service Corps, who shall be appointed by the Secretary of the Army from among the officers of the Medical Service Corps whose regular grade is above captain;

((2)) the assistant chiefs of the Medical Service Corps, who shall be designated by the Surgeon General from officers in that Corps and who shall be his consultants on activities relating to their sections;

((3)) commissioned officers of the Regular Army appointed therein;

((4)) other members of the Army assigned thereto by the Secretary of the Army; and

((5)) the following sections—

((A)) the Administrative Health Services Section;

((B)) the Medical Allied Sciences Section;

((C)) the Preventive Medicine Sciences Section;

((D)) the Clinical Health Sciences Section; and

((E)) other sections considered necessary by the Secretary of the Army.