| Popis: |
The mitotic indices and the nuclear DNA content of the cells of the meristematic apical zone of Fucus spiralis were investigated on young thalli 5,15, and 25 mm high. The apical cell exhibits a cell cycle with a prominent G2 phase whereas the segmental derivatives, the small cells of the promeristem and, the surrounding elongating cells are characterized by a preponderant G1 phase of their cycle.All the meristematic territories in the three sizes of plant studied show weak mitotic indices (0.5–1%). No significant difference is observed in the cycle features between the cells of the promeristem and the periapical zone of elongation. Hence, no change is seen in the mitotic activity of the cells which begin to differentiate. Certain similarities of structure and function among the shoot meristems of Cryptogams with a single apical cell are discussed. |
