de Campos Vidal B, Mello M L, Caseiro-Filho A C, Godo C
Acta Histochem. 1980;66(1):32-9. doi: 10.1016/S0065-1281(80)80079-1.
Form birefringence curves were determined for fixed (and unfixed rat axons before and after lipid extraction. The total detected birefringence was assumed to be due to the macromolecular array of myelin sheath components (phospholipids, cholesterol, and proteins). Unfixed nerves displayed negative form birefringence. Their form birefringence curve exhibited a = refractive index match point positioned at n = 1.46 (intrinsic birefringence). Formalin fixation induced decrease in the optical retardation values but did not affect the profile of the form birefringence curves. After lipid removal, however, the anisotropic patterns of the fixed and unfixed nerves changed. A positive form birefringence was then exhibited, which is attributed to the macromolecular orientation of the protein framework of the myelin sheath. Changes in the shape of the form birefringence curve and in the localization (and number) of the refractive index match point were found. They varied as lipids had been removed from nerves subjected or not to fixation. Therefore, the form birefringence of the myelin sheath proteins plays a part in the total phenomen observed in the whole nerves interfering with that displayed by phospholipids and cholesterol of the mentioned structure.
测定了固定的（以及脂质提取前后未固定的大鼠轴突的）形态双折射曲线。假定检测到的总双折射是由于髓鞘成分（磷脂、胆固醇和蛋白质）的大分子排列所致。未固定的神经呈现负形态双折射。它们的形态双折射曲线显示在n = 1.46（固有双折射）处有一个折射率匹配点。福尔马林固定导致光学延迟值降低，但不影响形态双折射曲线的轮廓。然而，脂质去除后，固定和未固定神经的各向异性模式发生了变化。此时呈现正形态双折射，这归因于髓鞘蛋白质框架的大分子取向。发现形态双折射曲线的形状以及折射率匹配点的定位（和数量）发生了变化。它们因脂质已从经过或未经过固定的神经中去除而有所不同。因此，髓鞘蛋白质的形态双折射在整个神经中观察到的总现象中起作用，干扰了上述结构中磷脂和胆固醇所显示的现象。
