[Ultrastructural findings on cell extrusion of intestinal villi in mice]

Ultrastructural findings at the extrusion zone on the tips of the Villi intestinales in the jejunum of mice showed that the estrusion of cells can take place in various ways. One possibility is that, at first, a part of the cell is protruding into the lumen under reduction or loss of the microvilli. The rest of the cell is following, but the continuity of the epithelium is preserved. The cell remains adhered to its neighbours which adjoin in such a way that not gap can develop in the epithelium. Often the plasmalemma of the extruding cell is completely preserved. Sometimes a breaking up can be observed. Then the cytoplasm enters the intestinal lumen. On the other hand, the enterocyte can leave the epithelium after widening of the intercellular space and destruction of the cell connection. Then a gap is established and direct contact between the intestinal lumen and the basement membrane.