 Menstrual cycle 4: End-of-study visit This visit will be about 10 days after the start of menses. Blood and urine will be collected for routine laboratory safety and pregnancy tests, tests for HIV, and immunology tests. The volunteers will also have a cervico-vaginal examination, during which sampling of secretions and cells will be done for immunology tests, and a full medical examination. A photograph of the cervix will be taken. This visit concludes the subjects participation in the study. 