Lloyd C W, Wells B
J Cell Sci. 1985 Apr;75:225-38. doi: 10.1242/jcs.75.1.225.
Root hairs have sometimes provided contradictory evidence for microtubule/microfibril parallelism. This tissue was re-examined using optimized conditions for the fixation, before immunofluorescence, of root hairs. In phosphate buffer, microtubules did not enter the apical tip of radish root hairs and were clearly fragmented. However, in an osmotically adjusted microtubule-stabilizing buffer, microtubules were observed within the apical dome and appeared unfragmented. Microtubules are not, therefore, absent from the region where new cell wall is presumed to be generated during tip growth. A spiralling of microtubules was seen at the apices of onion root hairs. Using shadow-cast preparations of macerated radish root hairs, it was confirmed that steeply helical microtubules matched the texture of the inner wall. In onion, the 45 degrees microtubular helices are accompanied by similarly wound inner wall fibrils. Results do not support the view that microtubules are not involved in the oriented deposition of fibrils in root hairs. Instead, they are interpreted in terms of a flexible helical cytoskeleton, which is capable of changing its pitch but is sensitive to fixation conditions.
根毛有时会提供关于微管/微纤丝平行排列的矛盾证据。在免疫荧光之前，使用优化的固定条件对该组织中的根毛进行了重新检查。在磷酸盐缓冲液中，微管没有进入萝卜根毛的顶端，并且明显断裂。然而，在经过渗透压调节的微管稳定缓冲液中，在顶端圆顶内观察到微管，并且看起来没有断裂。因此，在顶端生长过程中推测会产生新细胞壁的区域中并非没有微管。在洋葱根毛的顶端观察到微管呈螺旋状。使用浸渍的萝卜根毛的投射阴影标本，证实了陡峭的螺旋状微管与内壁的纹理相匹配。在洋葱中，45度的微管螺旋伴随着同样缠绕的内壁纤丝。结果不支持微管不参与根毛中纤丝定向沉积的观点。相反，它们可以用一种灵活的螺旋细胞骨架来解释，这种细胞骨架能够改变其螺距，但对固定条件敏感。
