The [6B.sup.22] cell pair develops into the parapolar cells, while the [6B.sup.11], [6B.sup.12], and [6B.sup.21] cell pairs eventually form a syncytium, which is more conspicuously stained with hematoxylin than the other cells (Fig.
The peripheral cells are composed of two parapolar cells and two uropolar cells.
The [5B.sup.21] and [5B.sup.22] pair undergo no further divisions and become the propolar cells and parapolar cells, respectively (Fig.
The head peripheral cells are composed of four propolar cells and parapolar cells. The propolar cells have short, dense cilia and form the calotte, which is more conspicuously stained with hematoxylin than the other cells.
The peripheral cells of the head region are composed of four propolar cells, four metapolar cells, and two parapolar cells. The propolar and metapolar cells have short, dense cilia and form the calotte.