Teardrop cells (Dacrocytes) are thought to form as a result of the removal of an inclusion from the cell as it moves through the spleen. This process is referred to as pitting. Since red cells are quite flexible and usually return to their normal shape following pitting, it has been theorized that in this case the membrane may have been stretched too far and thus cannot return to its original shape. The arrows in this image point to several teardrop cells.
