Heimfeld S, Bode H R
J Cell Sci. 1981 Dec;52:85-98. doi: 10.1242/jcs.52.1.85.
The interstitial cell of hydra is a multipotent stem cell, which produces nerve cells as one of its differentiated cell types. The amount of interstitial cell commitment to nerve differentiation varies in an axially dependent pattern along the body column. The distribution of nerve cell density has the same equivalent axial pattern. These facts have led to speculation that the regulation of nerve cell commitment is dictated by the nerve cell density. We examined this question by assaying interstitial cell commitment behaviour in 2 cases where the normal nerve cell density of the tissue had been perturbed: (1) in epithelial hydra in which no nerve cells were present; and (2) in hydra derived from regenerating-tip isolates in which the nerve density was increased nearly 4-fold. We found no evidence of regulation of nerve cell commitment in response to the abnormal nerve cell densities. However, the typical axial pattern of nerve commitment was still obtained in both sets of experiments, which suggests that interstitial cell commitment to nerve differentiation is dependent on some parameter of axial location that is not associated directly with the local nerve cell density.
水螅的间质细胞是一种多能干细胞，它能产生神经细胞作为其分化细胞类型之一。间质细胞向神经分化的程度沿着身体柱体以轴向依赖的模式变化。神经细胞密度的分布具有相同的等效轴向模式。这些事实引发了一种推测，即神经细胞分化的调控是由神经细胞密度决定的。我们通过检测两种组织正常神经细胞密度受到扰动的情况下间质细胞的分化行为来研究这个问题：（1）在上皮水螅中，不存在神经细胞；（2）在源自再生顶端分离物的水螅中，神经密度增加了近4倍。我们没有发现神经细胞分化受异常神经细胞密度调控的证据。然而，在两组实验中仍然获得了典型的神经分化轴向模式，这表明间质细胞向神经分化依赖于轴向位置的某些参数，而这些参数与局部神经细胞密度没有直接关联。
