<P> Because the epithelium is often under external stress and is somewhat delicate, the lamina propria hosts many immune cells . In the intestinal tract the immune system must have tolerance to the normal intestinal flora, yet respond to pathogenic microorganisms . Imbalance of this causes inflammation diseases such as inflammatory bowel disease . The lamina propria's richness in macrophages and lymphoid cells makes it a key place for immune responses to occur . It forms part of the barrier that protects internal tissues from external pathogenic microorganisms, especially from the gastrointestinal tract . </P> <P> The myofibroblasts in the lamina propria make it a very important contributor of inflammation and wound healing responses . Myofibroblasts are capable of releasing cytokines and chemokines in response to stress . Also their contractile capacity may help pull tissue together in the wound healing mechanism . </P> <P> Progression of epithelial cancer often relies on deep and regional lymph node invasion The lamina propria being one of the barriers to the submucosa is an area where epithelial cancer invasion is of significance since lymphatic invasion is an independent predictor of lymph node metastasis, especially in gastric cancer . As soon as the tumors breach the basement membrane and reach the lamina propria, they are exposed to lymphatics which may increase the rate of metastasis and cancer progression . Deeper invasion into the submucosa will increase the exposure to lymphatics . </P> <P> Long - standing inflammation is a risk factor for the development of cancer . The lamina propria macrophages when under much stress release pro-inflammatory signals that may lead to increased probability of developing cancer . An example of this is the over activation of the IL - 6 / STAT3 pathway, which has been linked to colitis - associated cancer . </P>

What is the function of the lamina propria