Salmonella typhimurium initiates murine infection by penetrating and destroying the specialized epithelial M cells in Peyer's patches. The study used a ligated intestinal loop model to examine the interactions between S. typhimurium and murine intestinal tissue. Invasive S. typhimurium strains were found to enter M cells within the follicle-associated epithelium (FAE) of Peyer's patches, while noninvasive strains could not. At 60 minutes, internalized invasive S. typhimurium were cytotoxic to M cells, leading to their destruction and creating gaps in the FAE that allowed bacteria to invade adjacent enterocytes. Later in the infection process, bacteria were found beneath the FAE, and replicating Salmonella began to enter both the apical and basolateral surfaces of enterocytes adjacent to infected M cells. Salmonella species cause infections ranging from asymptomatic carriage to systemic enteric fevers. Infection begins when invasive organisms pass through the epithelial surface of the small bowel. The study found that invasive S. typhimurium preferentially invade M cells in the terminal ileum, which are specialized cells found in the FAE. These cells are believed to play an active role in sampling antigens from the bowel. The study also showed that invasive S. typhimurium can cause damage to the FAE and lead to the death of M cells, which allows bacteria to invade enterocytes and spread further into the intestinal tissue. The study used a ligated intestinal loop model to examine the interactions between S. typhimurium and murine intestinal tissue. The results showed that invasive S. typhimurium preferentially invade M cells, which are specialized cells found in the FAE. These cells are believed to play an active role in sampling antigens from the bowel. The study also showed that invasive S. typhimurium can cause damage to the FAE and lead to the death of M cells, which allows bacteria to invade enterocytes and spread further into the intestinal tissue. The study also found that noninvasive S. typhimurium strains could not enter M cells or enterocytes, and did not cause damage to the FAE. The study concluded that the invasion of M cells by invasive S. typhimurium is a critical first step in the establishment of infection.Salmonella typhimurium initiates murine infection by penetrating and destroying the specialized epithelial M cells in Peyer's patches. The study used a ligated intestinal loop model to examine the interactions between S. typhimurium and murine intestinal tissue. Invasive S. typhimurium strains were found to enter M cells within the follicle-associated epithelium (FAE) of Peyer's patches, while noninvasive strains could not. At 60 minutes, internalized invasive S. typhimurium were cytotoxic to M cells, leading to their destruction and creating gaps in the FAE that allowed bacteria to invade adjacent enterocytes. Later in the infection process, bacteria were found beneath the FAE, and replicating Salmonella began to enter both the apical and basolateral surfaces of enterocytes adjacent to infected M cells. Salmonella species cause infections ranging from asymptomatic carriage to systemic enteric fevers. Infection begins when invasive organisms pass through the epithelial surface of the small bowel. The study found that invasive S. typhimurium preferentially invade M cells in the terminal ileum, which are specialized cells found in the FAE. These cells are believed to play an active role in sampling antigens from the bowel. The study also showed that invasive S. typhimurium can cause damage to the FAE and lead to the death of M cells, which allows bacteria to invade enterocytes and spread further into the intestinal tissue. The study used a ligated intestinal loop model to examine the interactions between S. typhimurium and murine intestinal tissue. The results showed that invasive S. typhimurium preferentially invade M cells, which are specialized cells found in the FAE. These cells are believed to play an active role in sampling antigens from the bowel. The study also showed that invasive S. typhimurium can cause damage to the FAE and lead to the death of M cells, which allows bacteria to invade enterocytes and spread further into the intestinal tissue. The study also found that noninvasive S. typhimurium strains could not enter M cells or enterocytes, and did not cause damage to the FAE. The study concluded that the invasion of M cells by invasive S. typhimurium is a critical first step in the establishment of infection.