Moody-Corbett F, Cohen M W
J Neurosci. 1981 Jun;1(6):596-605. doi: 10.1523/JNEUROSCI.01-06-00596.1981.
Myotomal muscle cells, derived from Xenopus embryos and grown in culture without nerve, develop discrete sites of cholinesterase (ChE) activity on their surface. The spatial relationship of these ChE patches to surface patches of acetylcholine receptors (AChRs) has been examined in the present study by a combination of ChE histochemistry and fluorescent staining of the receptors. ChE patches and AChR patches developed as early as the 1st day in culture and exhibited a high incidence of spatial overlap. The frequency of overlap varied with the age of the culture and ranged from 50 to 98% for patches on the lower cell surface (facing the floor of the culture dish) and from 28 to 79% for patches on the upper cell surface. The high incidence of overlap cannot be explained on the basis of a random distribution of patches since both types of patch occupied less than 3% of the cell surface. ChE and AChR patches also developed when cultures were grown in a serum-free medium as well as when cultures were prepared from young embryos in which muscle innervation had not yet begun. At some patches, the surface membrane was invaginated and at these invaginations, there was also a high incidence of overlap between the ChE and AChR stains. It is concluded that the mechanisms involved in the localization of AChRs and ChE on the surface of Xenopus myotomal muscle cells tend to be closely linked and operate even in the absence of innervation, previous contact by nerve, or electrical and contractile activity. Considered together with previous ultrastructural observations, the present findings suggest that these cells develop elaborate postsynaptic-like specializations even in the absence of neural factors.
源自非洲爪蟾胚胎且在无神经的情况下于培养中生长的肌节肌细胞，在其表面形成了离散的胆碱酯酶（ChE）活性位点。在本研究中，通过ChE组织化学与受体荧光染色相结合的方法，研究了这些ChE斑块与乙酰胆碱受体（AChR）表面斑块之间的空间关系。ChE斑块和AChR斑块早在培养的第1天就已形成，并且在空间上有很高的重叠发生率。重叠频率随培养时间而变化，培养皿底部（面向培养皿底部）的细胞表面斑块重叠频率为50%至98%，培养皿上部细胞表面斑块的重叠频率为28%至79%。由于两种类型的斑块均占细胞表面不到3%，因此重叠的高发生率无法用斑块的随机分布来解释。当培养物在无血清培养基中生长时，以及当从尚未开始肌肉神经支配的幼胚制备培养物时，ChE和AChR斑块也会形成。在一些斑块处，表面膜内陷，在这些内陷处，ChE和AChR染色之间也有很高的重叠发生率。结论是，非洲爪蟾肌节肌细胞表面AChR和ChE定位所涉及的机制往往紧密相连，即使在没有神经支配、先前与神经接触或电活动及收缩活动的情况下也能发挥作用。结合先前的超微结构观察结果来看，目前的研究结果表明，即使在没有神经因素的情况下，这些细胞也会发育出精细的突触后样特化结构。
