Mohamed M E I, El-Shaarawy E A A, Youakim M F, Shuaib D M A, Ahmed M M
Department of Anatomy and Embryology, Faculty of Medicine, Cairo University, Cairo, Egypt.
Folia Morphol (Warsz). 2019;78(2):237-258. doi: 10.5603/FM.a2018.0075. Epub 2018 Aug 29.
Degenerative changes caused by aging may affect the eye, especially the retina. Such changes occur as a part of normal physiological process and may be irreversible. The aim of the study was to demonstrate the influence of aging on the morphology of the retina to provide a basis to explain the pathogenesis of age-associated decline in visual acuity, scotopic and photopic sensitivity.
Forty male albino rats were used and divided into four age groups (group I: age of cortical maturity, group II: middle-aged, group III: aged group and group IV: senile group). The rats were sacrificed, the eye balls were enucleated. Intra-vitreal injections of formalin for haematoxylin and eosin and immunohistochemical sections, glutaraldehyde for toluidine blue semithin and E/M ultra-thin sections were performed. Measurements and quantitative histomorphometric estimation of the layers of the retina were done.
Light microscopic examination revealed age-dependent attenuation of photoreceptor striations. Aged and senile groups presented pyknotic, widely- -spaced nuclei of the outer nuclear layer. The inner nuclear layer was thinned out to 2 or 3 cellular rows. Retinal capillaries showed progressive dilatation and congestion. Statistical analysis proved significant thinning of the retina with variable degrees of thinning of the constituting layers. Decreased arborisation with age was confirmed with quantification of synaptophysin-immunostained sections. Glial fibrillary acidic protein immunostaining revealed the picture of reactive gliosis. On the ultrastructural level, the retinal pigment epithelium exhibited major alterations with aging. Numerous phagosomes, lipofuscin and melanolipofusin granules appeared within the cells, together with exaggerated basal infoldings. The pho- toreceptor nuclei became degenerated and the perinuclear space was widened.
Rat retinae clearly undergo age-related morphological changes. Such changes provide a cellular base for explanation of decreased vision in humans with aging other than reflection errors. Effect of aging was not only qualitative, but also quantitative.
衰老引起的退行性变化可能会影响眼睛，尤其是视网膜。这些变化是正常生理过程的一部分，可能是不可逆的。本研究的目的是证明衰老对视网膜形态的影响，为解释与年龄相关的视力、暗视觉和明视觉敏感度下降的发病机制提供依据。
使用40只雄性白化大鼠，分为四个年龄组（第一组：皮质成熟期；第二组：中年组；第三组：老年组；第四组：高龄组）。将大鼠处死，摘除眼球。进行玻璃体内注射福尔马林用于苏木精和伊红染色及免疫组织化学切片，注射戊二醛用于甲苯胺蓝半薄切片和电子显微镜超薄切片。对视网膜各层进行测量和定量组织形态计量学评估。
光学显微镜检查显示光感受器条纹随年龄增长而减弱。老年组和高龄组外核层细胞核固缩、间距增宽。内核层变薄至2或3个细胞行。视网膜毛细血管显示出逐渐扩张和充血。统计分析证明视网膜明显变薄，各组成层有不同程度的变薄。通过对突触素免疫染色切片的定量分析证实，随着年龄增长树突分支减少。胶质纤维酸性蛋白免疫染色显示有反应性胶质增生。在超微结构水平上，视网膜色素上皮随着衰老出现主要改变。细胞内出现大量吞噬体、脂褐素和黑素脂褐素颗粒，同时基底褶皱增多。光感受器细胞核发生退变，核周间隙增宽。
大鼠视网膜明显经历与年龄相关的形态学变化。这些变化为解释除屈光不正外人类衰老时视力下降提供了细胞基础。衰老效应不仅是定性的，也是定量的。
