. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CELL DIVISION IN AXIAL POLYP OF 813. - 1200 1500 1800 2100 2400 0200 Time of day 0600 0900 1200 FIGURE 1. Diel pattern of percentage division () of cells from the endoderm (solid circles) and cells from the calicoblastic ectoderm (open circles). Each point is the average of two determinations from each time period; the vertical bars indicate the range of the two values. Note that the two values for the calicoblastic ectoderm at 1500 were the same, hence no range bar. columnar cells) but also 2 mm from the t
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CELL DIVISION IN AXIAL POLYP OF 813. - 1200 1500 1800 2100 2400 0200 Time of day 0600 0900 1200 FIGURE 1. Diel pattern of percentage division () of cells from the endoderm (solid circles) and cells from the calicoblastic ectoderm (open circles). Each point is the average of two determinations from each time period; the vertical bars indicate the range of the two values. Note that the two values for the calicoblastic ectoderm at 1500 were the same, hence no range bar. columnar cells) but also 2 mm from the tip (the extent of the region surveyed for the determination of mitotic indices) and up to 10 mm from the tip as well. No narrow zone of cell proliferation is apparent; cells divide at random points throughout the column. DISCUSSION The axial polyp of Acropora cervicornis contains dividing cells from the tip to at least 10 mm proximal to the tip in both the endoderm and the calicoblastic ectoderm. These results are similar to those found by David and Campbell (1972) for the hydrozoan polyp Hydra attenuata and by Minasian (1980) for the anthozoan (actini- arian) polyp Haliplanella luciae. Both studies described proliferating cells among all epithelial layers. In addition, David and Campbell (1972) showed that the number of divisions observed in the endodermal and ectodermal tissue were enough to account for the observed growth of those cell populations; migration of cells from one epithelial layer to another probably did not occur. Until more is known about the cell cycle kinetics of A. cervicornis, it cannot be stated with certainty that the mitotic indices observed in this study would result in a sufficient increase in cell population to account for the observed growth rate of the polyp. However, the magnitude of the mitotic indices in the endoderm and the calicoblastic ectoderm of A. cervicornis is the same as that seen in Hydra attenuata (David and Campbell, 1972) and H. viri
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
