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.
Frequent bouts of watery diarrhea are the main symptom of shigellosis. Abdominal cramping, nausea, and vomiting may also occur. Many people who have shigellosis also have either blood or mucus in their stool, and they may run a fever. Symptoms usually begin within 3 days of coming in contact with Shigella. In some cases, however, symptoms of infection may appear as much as a week after contact. Diarrhea and other signs of shigellosis usually last between 2 and 7 days. Mild infection lasting a couple of days may not require treatment.