晶体和白内障-解剖.

Lens Epithelium上皮细胞
Lens Epithelium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）
Perhaps the most dramatic morphologic change occurs when the epithelial cells elongate to form lens fiber cells. This change is associated with a tremendous increase in the mass 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 organelles is optically advantageous, because light passing through the lens is no longer absorbed or scattered by these structures. However, because these new lens fiber cells lack the metabolic functions previously carried out by the organelles, they are now dependent on glycolysis for energy production
Lens and Cataract
S11CH01 Anatomy 郑亚洁
Normal Crystalline Lens



Transparent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
晶体由纤细而坚韧的悬韧带悬吊于睫状体间
Normal Crystalline Lens



The lens is composed of the capsule, lens epithelium , 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
Nucleus and Cortex核和皮质

新产生的纤维包绕旧纤维，并将它们推向 中央，胎儿核始终在晶体最中央，最新的 纤维在最外层组成皮质
Normal Crystalline Lens
maintain its own clarity 透明性 refract light 屈光力
provide accommodation
调节力
Normal 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.
Байду номын сангаас
Capsule囊



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
Zonular Fibers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 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 Epithelium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
Normal Crystalline Lens




index 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60D Cornea角膜40-45D
Normal Crystalline Lens


The lens continues to grow 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hyperopic