False-colour transmission electron micrograph (TEM) of a rod-like bacterium,Mycobacterium tuberculosis,the causative agent of tuberculosis in humans. This bacterium forms filamentous,branching structures,which are inhaled into the lungs to form a primary tubercle,an initial focus of infection; spread takes place via adjacent lymph nodes. This form is called pulmonary tuberculosis or consumption & phthisis (wasting). Many people are infected without showing symptoms,whilst the body's immune system holds the disease in check. They remain carriers,transmitting the bacilli by coughing or sneezing. Magnification: x18,000 at 35mm size,x36,000 at 6x7cm size |