exists and is an alternate of . The sperm that reach the egg swim into it and attempt to penetrate the zona pelluca, which is the semi permeable outer membrane of the egg. Some sperm have a shape which makes this relatively easy, and others which are poorly formed are likely to have more difficulty.
1 Shigellosis is an infectious disease caused by a group of bacteria called Shigella. 2  Symptoms of Shigella infection include diarrhea (often bloody), fever, and stomach cramps starting a day or two after exposure to the bacteria. 3  Shigellosis usually resolves in 5 to 7 days.
slide 4 of 5. Shigella Bacterium Shigella is a group of bacteria that cause shigellosis, a type of bacterial infection that affects the lining of the intestines. The most common sources of this bacteria exist in areas that have poor sanitation and crowded living conditions.