Bode P M, Bode H R
Developmental Biology Center, University of California, Irvine 92717.
Development. 1987 Jan;99(1):89-98. doi: 10.1242/dev.99.1.89.
The tentacles in hydra have characteristics of both spacing patterns and number-regulating patterns in that their number under some circumstances changes with the size of the animal and under others does not. To determine which type of processes could yield these results, an extensive analysis was undertaken of the size parameters pertinent to tentacle formation. To do this pieces of tissue, varying in shape and spanning a 30-fold size range, were excised and allowed to regenerate into complete animals. Three separate mechanisms were found to combine which resulted in the final number of tentacles: (1) the spread of the two-part head pattern to produce a competent band of tissue of a given size where the tentacles could form; (2) initiation of tentacle-forming centres by a spacing mechanism and (3) growth of the tentacles to a size proportional to the size of the animal.
水螅的触手具有间隔模式和数量调节模式的特征，因为在某些情况下，它们的数量会随着动物体型的变化而变化，而在其他情况下则不会。为了确定哪种类型的过程可以产生这些结果，我们对与触手形成相关的大小参数进行了广泛分析。为此，我们切除了形状各异、大小范围跨度达30倍的组织块，并让它们再生为完整的动物。我们发现有三种不同的机制共同作用，决定了触手的最终数量：（1）两部分头部模式的扩散，以产生一个给定大小的能形成触手的组织带；（2）通过间隔机制启动触手形成中心；（3）触手生长到与动物体型成比例的大小。
