The Morphological Study Of Peritoneal Mesothelial Cell And Lymphatic Stomata During Metastasis Of HepA-H Cells

Background:Mesothelial cells cover the entire surface of the three serosal cavities and the internal organs.The mesothelial cells have many functions including protection,immune response,transportation and so on.Lymphatic stomata are small openings of lymphatic capillary on the free surface of mesothelium.The peritoneal cavity and pericardial cavity are connected with lymphatic system via these small openings which have the function of active absorption.Dissemination of tumors requires four steps:detachment of cancer cells from the primary tumor,attachment to distant peritoneum,invasion into subperitoneal space,and proliferation.Changes of mesothelial cells happen during the dissemination of tumor cells.Objective:To study the morphological changes of peritoneal mesothelial cells and lymphatic stomata on the diaphragm and mesentery during the dissemination of HepA-H cells.Methods:After injection of HepA-H ascites tumor to the peritoneal cavity, diaphragm and mesentery were observed by SEM at different time point.The fluid of ascites tumor was injected to the peritoneal cavity for 3 days.Then the two tissues were examined by SEM.Migration ability of HepA-H cells were tested by Boyden chamber.VEGF level was assayed with ELISA kit.Mesothelial cells from mesentery were cultured in vitro.Results:Compared to the control,the weight of mice showed an obvious growth. The growth speed decreased after the 11^th day since injection of HepA-H.Death occurred in the 14^th day.Morphological changes was observed during dissemination of ascites tumor.The stomata showed larger in size and quantity both on diaphragm and on mesentery.Tumor cells were also seen in the stomata.The migration ability tested by Boyden chamber was 23.4±1.5%.VEGF level in ascites was 5.43±0.23ng/ml.The morphological observation and immunofluorescence staining tests proved the cells collected from mesentery were mesothelial cells.Conclusion:Mesothelial cells on diaphragm showed tumid cell bodies,enlarged spaces between mesothelial cells,and increased microvilli during metastasis of tumor cells.Tumor cells were also observed planting between the mesothelial cells.Little morphological change were shown in mesenteric mesothelial cell.Nodular tumor cells can be seen in the late.Tumor cells were also seen getting through the lymphatic stomata.