Tilney L G
J Cell Biol. 1978 May;77(2):551-64.
Between the acrosomal vacuole and the nucleus is a cup of amorphous material (profilactin) which is transformed into filaments during the acrosomal reaction. In the center of this cup in untreated Thyone sperm is a dense material which I refer to as the actomere; it is composed of 20-25 filaments embedded in a dense matrix. To visualize the substructure of the actomere, the profilactin around it must be removed. This is achieved either by demembranating the sperm with Triton X-100 and then raising the pH to 8.0, or by adding inophores to intact sperm at pH 8.0. Under these conditions, the actomere remains as a unit while the rest of the profilactin is solubilized or polymerized. When demembranated sperm are incubated under conditions in which the actin should polymerize, filaments grow from the end of the actomere: the actomere thus appears to behave as a nucleating body. This observation is strengthened by experiments in which untreated sperm are incubated in seawater or isotonic NaCl at pH 7.0 and the ionophore X537A is added; in this case, only a partial polymerization of the actin occurs and the acrosomal vacuole does not fuse with the cell surface. The actin filaments that do form, however, are attached to the apical end of the actomere. In fact, the elongating filaments push their way into and frequently through the acrosomal vacuole. Thus, it appears that the sperm organizes the actin filaments by controlling their nucleation. My model is that the cell controls the ammount of unbound actin such that it is slightly above the critical concentration for polymerization. Then, spontaneous nucleation is unfavored and polymerization would proceed from existing nuclei such as the actomer.
顶体泡与细胞核之间是一杯无定形物质（肌动蛋白原），在顶体反应过程中它会转化为细丝。在未处理的海胆精子的这个杯状结构中心是一种致密物质，我将其称为动粒；它由嵌入致密基质中的20 - 25根细丝组成。为了观察动粒的亚结构，必须去除其周围的肌动蛋白原。这可以通过用Triton X - 100使精子去膜，然后将pH值提高到8.0来实现，或者通过在pH值为8.0时向完整精子中添加离子载体来实现。在这些条件下，动粒作为一个整体保留下来，而其余的肌动蛋白原则被溶解或聚合。当去膜精子在肌动蛋白应该聚合的条件下孵育时，细丝从动粒末端生长出来：因此动粒似乎起到了成核体的作用。通过将未处理的精子在pH值为7.0的海水或等渗氯化钠中孵育并添加离子载体X537A的实验，这一观察结果得到了加强；在这种情况下，肌动蛋白只发生部分聚合，顶体泡也不会与细胞表面融合。然而，形成的肌动蛋白丝附着在动粒的顶端。实际上，伸长的细丝会挤入并常常穿过顶体泡。因此，似乎精子通过控制肌动蛋白丝的成核来组织它们。我的模型是，细胞控制未结合肌动蛋白的量，使其略高于聚合的临界浓度。然后，自发成核不受青睐，聚合将从现有的核如动粒开始进行。
