快速退变性视网膜变性感光细胞超微结构变化分析

目的 了解快速退变性遗传性视网膜变性的感光细胞在出生后早期发生的形态学变化,为临床治疗提供依据.方法 取出生后不同时间的rd小鼠及正常对照小鼠各6只的视网膜,经光镜、扫描电镜和透射电镜观察感光细胞的形态发生发育和结构变化过程,比较二者的动态变化和形态学差异.结果 rd鼠生后1周开始出现感光细胞节段变短,内节段内线粒体变性改变多见;偶见感光细胞核旁胞浆内出现肿胀变形的线粒体.2周时节段层变薄,内节段结构已不完整,外节膜盘少见,变形且排列不整齐;外核层细胞层数明显减少,可见核固缩及染色质凝聚,偶见外丛状层部分神经突起内出现变性的线粒体.3周时节段层近消失,外核层只剩一层细胞,胞浆内可见髓样结构;外丛状层变薄.4周时内节段高度变形,视网膜色素上皮层与外核层之间出现大量不成形结构.外核层仅残存少许胞体,胞浆内出现多量不成形结构.外丛状层极薄,部分区域已消失.结论 rd鼠在出生后早期就发生感光细胞的变性改变,细胞内线粒体改变明显.其感光细胞变性发生早,进展快,呈快速退变特点.

Analysis of ultra structural changes of retinal photoreceptors in animal models with fast retinal degeneration

Objective To investigate the morphological changes of retinal photoreceptors during the early postnatal period in hereditary fast retinal degeneration,aiming at providing some basic knowledge to the clinical treatment.Methods Retinas of six rd mice and six normal control mice were observed at different postnatal time.Microscopic structure and ultra structure of retinal photoreceptors were observed under light microscopy,scanning electron microscopy and transmission electron microscopy,and changes were compared between the two groups.Results In rd mice,the segments became shorter on PN-1W (postnatal 1 week).Mitochondria degeneration was seen mostly in the inner segment and merely in the cytoplasm beside the nucleus.On PN-2W,the segment layer became thinner.Integrity of inner segments was destructed.The outer segments reduced and deformed.Pyknotic nuclei and condense of chromosome could be seen.Mitochondria degeneration was observed in some neuritis of the outer plexiform layer.On PN-3W,segment layer almost disappeared.There's only one layer left in the outer nuclear layer.Myelin bodies appeared in the cytoplasm of the photoreceptors.The outer plexiform layer became thinner.On PN-4W,inner segments deformed greatly.Only a few degenerated photoreceptors left.Masses of disorganized structures appeared in the cytoplasm,between RPE and the outer nuclear layer.The outer plexiform layer became very thin and disappeared in some areas.Conclusion The photoreceptors degenerate during the early postnatal period in rd mice,with obvious mitochondria degeneration.The photoreceptor degeneration begins early and develops fast.