It is the investigators hypothesis therefore that as a result of antigen presentation and stimulation within a specifically "genital tract milieu" T &B lymphocytes leaving the external iliac nodes as a result of an immunisation into the thigh will be patterned in such a way as to more likely home back to the cervix and vagina due to the common drainage of the cervix, vagina and thigh (Figure 1) into the external iliac and lateral aortic lymph nodes. In contrast, cells leaving the axillary lymph nodes after immunisation of the right arm will enter the blood directly via the right lymphatic duct and so will not pass through any lymph nodes in common with the cervix and vagina.