Purpose: To observe the development of optic nerve, we examined four optic nerves from Siameses Twins by absolute counts of axons.Methods: Mean axon diameter, mean axon density, totally axonal population and optic ner...Purpose: To observe the development of optic nerve, we examined four optic nerves from Siameses Twins by absolute counts of axons.Methods: Mean axon diameter, mean axon density, totally axonal population and optic nerve area were noted for each optic nerve. The mean axon diameter and the mean axon density were compared between paraxial (inner sectors)and cortical (outer sectors)areas of the nerves.Results: More myelinated axons were seen in the inner sectors as compared to the outer sectors(average 11 axons/1 000 μm2 in inner sectors and 34 axons/l 000 μm2 in outer sectors( P＝0. 036) . The myelinated fibers were also smaller(63 microns) in the outer sectors as compared to the inner sectors(72 microns) ( P ＝ 0. 001 ). The average cross sectors area for the four 40 week stage optical nerves of Siamese Twins was 3.32 × 103 as compared to 1 million axons for 32-week-old normals.Conclusion: Our finding of fewer axonal number and small myelinated fibers in the Siamese Twins suggests hypoplasia. Myelination was more abnormal in the paraxial optic nerve than that in the peripheral sectors, suggesting anomalous development of optic nerve peripherally and delayed developnent centrally. Axonal density is higher in inner sectors than that in outer sectors, suggesting delayed development of the outer nerve sector.展开更多
Objective To develop and evaluate the rat model of chronic glaucoma by episcleral veins ligation （EVL）. Methods Experimental glaucoma was induced unilaterally in 28 male Sprague-Dawley rats by ligating two episclera...Objective To develop and evaluate the rat model of chronic glaucoma by episcleral veins ligation （EVL）. Methods Experimental glaucoma was induced unilaterally in 28 male Sprague-Dawley rats by ligating two episcleral veins. Intraocular pressure （10P） in rats was measured by a Goldmann applanation tonometer under 3 % pentobarbital sodium anesthesia. The optic nerve head and retinal vasculature were assessed by repeated fundus examinations. The amount of optic nerve axons was assessed by Image-Pro Plus image analysis system in a masked fashion. Results lOP without EVL was （ 19.21 ± 1.23） mmHg, whereas the EVL eyes gained about 1.8-fold higher 10P[ （33.96 ±2. 73） mmHg]after EVL immediately （ P 〈 0. 001 ）. The elevated IOP gradually decreased over time. However, the differences were kept significant up to 8 weeks after EVL. The lOP was reduced to similar levels as contralateral eyes at 12 and 16 weeks after EVL. The glaucomatous optic nerve excavation appeared in EVL eyes at 8 weeks after EVL, and the optic nerve excavation enlarged gradually with the increasing post-operation time. The amount of optic nerve axons also significantly decreased in EVL eyes at 8 weeks after EVL, and the amount of axons decreased gradually with the increasing post-operation time. Conclusion Increase of lOP caused by EVL represents a useful and efficient model of experimental glaucoma in rats.展开更多
文摘Purpose: To observe the development of optic nerve, we examined four optic nerves from Siameses Twins by absolute counts of axons.Methods: Mean axon diameter, mean axon density, totally axonal population and optic nerve area were noted for each optic nerve. The mean axon diameter and the mean axon density were compared between paraxial (inner sectors)and cortical (outer sectors)areas of the nerves.Results: More myelinated axons were seen in the inner sectors as compared to the outer sectors(average 11 axons/1 000 μm2 in inner sectors and 34 axons/l 000 μm2 in outer sectors( P＝0. 036) . The myelinated fibers were also smaller(63 microns) in the outer sectors as compared to the inner sectors(72 microns) ( P ＝ 0. 001 ). The average cross sectors area for the four 40 week stage optical nerves of Siamese Twins was 3.32 × 103 as compared to 1 million axons for 32-week-old normals.Conclusion: Our finding of fewer axonal number and small myelinated fibers in the Siamese Twins suggests hypoplasia. Myelination was more abnormal in the paraxial optic nerve than that in the peripheral sectors, suggesting anomalous development of optic nerve peripherally and delayed developnent centrally. Axonal density is higher in inner sectors than that in outer sectors, suggesting delayed development of the outer nerve sector.
基金Supported by Shanghai Education Committee Project Foundation (06BZ040)
文摘Objective To develop and evaluate the rat model of chronic glaucoma by episcleral veins ligation （EVL）. Methods Experimental glaucoma was induced unilaterally in 28 male Sprague-Dawley rats by ligating two episcleral veins. Intraocular pressure （10P） in rats was measured by a Goldmann applanation tonometer under 3 % pentobarbital sodium anesthesia. The optic nerve head and retinal vasculature were assessed by repeated fundus examinations. The amount of optic nerve axons was assessed by Image-Pro Plus image analysis system in a masked fashion. Results lOP without EVL was （ 19.21 ± 1.23） mmHg, whereas the EVL eyes gained about 1.8-fold higher 10P[ （33.96 ±2. 73） mmHg]after EVL immediately （ P 〈 0. 001 ）. The elevated IOP gradually decreased over time. However, the differences were kept significant up to 8 weeks after EVL. The lOP was reduced to similar levels as contralateral eyes at 12 and 16 weeks after EVL. The glaucomatous optic nerve excavation appeared in EVL eyes at 8 weeks after EVL, and the optic nerve excavation enlarged gradually with the increasing post-operation time. The amount of optic nerve axons also significantly decreased in EVL eyes at 8 weeks after EVL, and the amount of axons decreased gradually with the increasing post-operation time. Conclusion Increase of lOP caused by EVL represents a useful and efficient model of experimental glaucoma in rats.
