Color enhanced SEM of Candida albicans, an opportunistic fungus (or form of yeast) yeast that normally inhabits the mouth, throat, intestines and genitourinary tract of most humans. C. albicans recognize and destroy harmful bacteria. The growth of C. albicans is usually controlled by the immune system and "friendly" bacteria. However, if the number of bacteria is decreased (through antibiotics), or the immune systems is weakened, C. albicans will shift from yeast to mycelial fungal form and start to invade the body. In this invasive fungal state it can produce rhizoids, root-like structures that can penetrate intestinal walls, allowing toxins, undigested food, bacteria, and yeast to enter the bloodstream. SEM 550x at 35mm.