Menstruation, periodic discharge from the vagina of blood, secretions, and disintegrating mucous membrane that had lined the uterus. 1  The biological significance of the process in humans can best be explained by reference to the reproductive function in other mammals.
Chlamydial (kla-MID-ee-al) infections are caused by three species of microorganisms. Chlamydia trachomatis can cause eye or lung infections and can also infect the urinary and genital areas of both men and women. Chlamydia pneumoniae causes infections of the respiratory tract, and Chlamydia psittaci causes an illness, known as parrot fever, that is similar to the flu.
C. trachomatis infections are the leading cause of sexually transmitted diseases in the United States. C. trachomatis is known to cause cervicitis, pelvic inflammatory disease (PID), epididymitis and proctitis. It is also the most frequent cause of non-gonococcal urethritis in men. Among women, the consequences of Chlamydial infections are severe if left untreated.