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.
The feces of infected individuals (1) and waters contaminated by infected feces (2) are also reservoirs of the pathogenic agent. General Characteristics. Shigella are gram-negative rods that are non-motile and non-sporeforming (2). The bacteria is primarily a human disease, but has been found in some primates (2).Shigella are facultative anaerobes, similar to enterics such as E. coli (3).eutrophils in the stool are an easily identifiable sign of Shigella infection (3). In the medical laboratory, identification of individual Shigella species is often accomplished through slide agglutination using absorbed rabbit antisera (3).