Electron Microscopy:
The counterpart of the signet-ring type tumor cells were seen
as groups of 2 to 4 cells joined by tight (occludens) junctions
and forming a moderate sized lumen lined by microvilli and containing
secretory material (Fig. 3). At higher magnification, microfilamentous
core rootlets (actin filaments) projected down from the microvilli
into the apical cytoplasm and the lumen contained glycocalyceal
bodies (Fig. 4). Other groups of tumor cells contained small intracytoplasmic
lumens with similar features associated with the microvilli and
secretory material within the lumen (Fig. 5).
|
|
|
| Figure 3. A group of 3 or 4 tumor cells are joined by tight junctions (arrows) and form a glandular lumen (L). Such a complex is the light microscopic counterpart of a signet-ring cell. | Figure 4. At higher magnification, the luminal cells have many short fairly uniformly sized microvilli. Projecting into the apical cytoplams from microvilli are core filaments (arrows). The lumen contains darkly staining secretory products and glycocalyceal bodies (GB). |
|
| Figure 5. Another group of tumor cells joined by an elongated tight junction (arrow). One tumor cell contains a small intracytoplasmic lumen (arrowhead) into which projects numerous microvilli. |
