SEM of Candida albicans, a yeast that inhabits the mouth, throat, intestines and urinary tract of 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), the immune systems is weakened, or other conditions for yeast proliferation occur (a diet high in sugar) C. albicans will shift from yeast to mycelial fungal form, producing rhizoids, root-like structures that penetrate intestinal walls, allowing toxins, undigested food, bacteria, and yeast to enter the bloodstream. Overgrowth of C. albicans can also lead to vaginitis and oral thrush. Magnification = x2,500 at 35mm.