Introduction. A broken arm or wrist is usually caused by a fall onto an outstretched arm. It typically takes about six to eight weeks to heal in adults, and less time in children. Doctors refer to all breaks or cracks in bones as fractures.Go to your nearest accident and emergency (A&E) department if you think you or your child has broken a bone.t typically takes about six to eight weeks to heal in adults, and less time in children. Doctors refer to all breaks or cracks in bones as fractures. Go to your nearest accident and emergency (A&E) department if you think you or your child has broken a bone.
In contrast, the overwhelming majority of antigens for T cells are proteins, and these must be fragmented and recognized in association with MHC products expressed on the surface of nucleated cells, not in soluble form.
T-dependent antigen one that requires the presence of helper T cells to stimulate antibody production by B cells; most antigens are T-dependent. T-independent antigen an antigen that can trigger B lymphocytes to produce antibodies without the participation of T lymphocytes. See also T-dependent antigen.