晶体和白内障-解剖

1、Lens and CataractS11CH01 Anatomy 郑亚洁Normal Crystalline LensNormal Crystalline LensTransparent透明Biconvex双凸no blood无血管no innervation 无神经Metabolic新陈代谢：aqueous humor房水posterior to the iris and anterior to the vitreous body 位于虹膜后玻璃体前maintain its own clarity透明性refract light屈光力provide accommodation调节力Norma

2、l Crystalline LensNormal Crystalline Lens The lens is suspended in position by the zonules of Zinn, which consist of delicate yet strong fibers that support and attach it to the ciliary body.晶体由纤细而坚韧的悬韧带悬吊于睫状体间 Normal Crystalline LensNormal Crystalline LensThe lens is composed of the capsule, lens e

3、pithelium , cortex, and nucleus晶体：囊，上皮细胞，皮质，核optic axis视轴穿过 晶体前后极equator晶体赤道部周长最长 Normal Crystalline LensNormal Crystalline Lensindex of refraction折射率： 中央centrally 1.4周边peripherally 1.36非调节状态lens 晶体：15-20D总屈光度约60DCornea角膜40-45DNormal Crystalline LensNormal Crystalline LensThe lens continues to grow

4、throughout life. 晶体一生持续生长出生：6.4mm *3.5mm，90mg 成人：9mm *5mm，255mg 老年：皮质增厚，晶体表面曲率增加 refractive power屈光力增加 晶体密度增加 index of refraction折射率下降 结果：近视myopic /远视hyperopicNormal Crystalline LensNormal Crystalline Lens透明transparent ，有弹性elastic上皮细胞分泌的IV型胶原collagen晶状体赤道前后最厚，后极中央最薄前囊出生时比后囊厚，且持续终生生长CapsuleCapsule囊囊Z

5、onular FibersZonular Fibers悬韧带悬韧带These fibers originate from basal laminae of the nonpigmented epithelium of the pars plana and pars plicata of the ciliary body 起源于睫状体平坦部及冠部 的无色素上皮细胞基底膜The zonular fibers insert, in a continuous fashion, on the lens capsule in the equatorial region, anteriorly 1.5 mm

6、 onto the anterior lens capsule and posteriorly 1.25 mm onto the posterior lens capsule. 附着于赤道部囊袋上，前囊1.5mm，后囊1.25mm年龄增长，悬韧带减少纤维直径5-30微米Lens EpitheliumLens Epithelium上皮细胞上皮细胞前囊下单层上皮细胞代谢活跃，合成：DNA,RNA, protein蛋白，lipid脂类及ATP供能有丝分裂在germinative zone生发区最旺盛新细胞migrate迁移至equator赤道部，在bow region弓形区最终分化成晶体纤维 Len

7、s EpitheliumLens Epithelium上皮细胞上皮细胞最戏剧性的变化：上皮细胞拉长纤维细胞纤维细胞：膜蛋白大量增加； 细胞器减少（细胞核，线粒体，核糖体） 利于光线穿过，不被吸收和阻挡 糖酵解功能（缺少细胞器代谢） Lens EpitheliumLens Epithelium上皮细胞上皮细胞Perhaps the most dramatic morphologic change occurs when the epithelial cells elongateto form lens fiber cells. This change is associated with a t

8、remendous increase in themass of cellular proteins in the fiber cell membranes. At the same time, the cells lose organelles,including cell nuclei, mitochondria, and ribosomes. The loss of these organellesis optically advantageous, because light passing through the lens is no longer absorbed orscattered by these structures. However, because these new lens fiber cells lack the metabolicfunctions previously carried out by the organelles, they are now dependent on glycolysisfor energy productionNucleus and CortexNucleus and Cortex核和皮质核和皮质新产生的纤维包绕旧纤维，并将它们推向中央，胎儿核始终在晶