Compartmentalization of anterogradely and retrogradely transported organelles in axons and growth cones from chick optic tectum

Previous work suggests that organelles contacting microtubules in axons are in fast transport. Here, we examine the distribution of organelles contacting microtubules in growing axons and growth cones from chick optic tectum. Five axon segments, each 10 microns long, and 4 entire growth cones were reconstructed from serial electron micrographs of quick-frozen, freeze-substituted chick optic tectum. Organelles contacting microtubules in axons are evenly distributed along all microtubules. Smaller organelles, presumably in anterograde transport, are enclosed in fascicles of microtubules, while larger organelles in retrograde transport lie outside the fascicles. In contrast, organelles contacting microtubules are prevalent only in the most proximal parts of the growth cone, before the microtubule fascicles splay out more distally. The distance between noncontacting organelles and microtubules also becomes progressively greater, reaching a maximum in the mid- and more distal region of the growth cone. Contacts with microtubules of both the smaller, presumably anterogradely transported organelles, as well as the larger, presumably retrogradely transported organelles, abruptly become less frequent in the proximal midregion of the growth cone. It is therefore of possible significance in stopping and starting microtubule-based organelle transport that microtubules change from a straight to an undulating configuration in the midregion of the growth cone. The decrease in organelle binding to microtubules at the demarcations between the straight and undulating microtubule segments may depend on proteins or other local factors as well as the splaying out of the microtubule bundles.     

健康和病变人声带振动特性声门图

本文用多功能声门图仪测定了健康受试者(男46名,女34名)和不同喉病患者(男134名,女87名)声门图的波形及其特征参数。根据测出的正常声门图及其参数分布研究了恶性喉病变、声带麻痹、喉内关节病变、功能性声门发声障碍、声带息肉、声带小结、喉炎和早期喉病的临床声门图表现及其与声带振动模式变异之间的关系,并探讨了上述病变声门图的鉴别诊断指标和用声门图对喉病手术治疗、药物治疗和功能治疗的疗效进行定性和定量评价。研究结果证实:声门图方法能准确、定量、灵敏地反映声带振动模式及其变异;在喉病诊治中具有重要的应用价值。     

Shape of the myopic eye as seen with high-resolution magnetic resonance imaging.

We have obtained multislice magnetic resonance (MR) images of the eye and calculated ocular dimensions along the three cardinal axes: antero-posterior (A-P), equatorial, and vertical. We found no difference in the shape of hyperopic (average refractive error: +3.72 D) and emmetropic eyes, both of which had an equatorial diameter longer than the A-P and vertical diameters. Myopic eyes (average refractive error: -6.54 D) were larger than hyperopic eyes, and most had the same spheroelliptical shape as that of the emmetropic and hyperopic eyes. The results suggest that during myopic progression an overall enlargement or a radial volume expansion has occurred.