Kusakari T, Sato T, Tokoro T
Department of Ophthalmology, School of Medicine, Tokyo Medical and Dental University, Japan.
Exp Eye Res. 1997 Mar;64(3):465-76. doi: 10.1006/exer.1996.0242.
Similar neurochemical events appear to be involved in the development of myopia in chicks and mammals. The rapid post-hatching development of the chick is ideal for studying experimental myopia. In this investigation, one eye of 2-day-old chicks was deprived of form vision for 2 weeks and then compared to the fellow, non-deprived eye by immunohistochemistry and light and electron microscopy. All deprived eyes showed a high refractive error and ocular enlargement. In deprived eyes, the posterior cartilaginous sclera was thicker and the fibrous sclera of the same section was thinner than the control. Scleral morphological changes were restricted to a central button 6-7 mm in diameter (the posterior pole) within the posterior hemisphere, further divided into posterotemporal and posteronasal parts. The most enlarged, posterior cartilaginous structure of deprived sclera could be divided into an inner and an outer zone. The inner zone had many unevenly-arranged chondrocytes, each having a well-developed granular endoplasmic reticulum and Golgi complex and a very irregular cell surface. Numerous S-phase cells and isogenous groups were detected in the outer zone. Hypertrophic chondrocytes were often observed in the innermost region of the outer zone and the outermost region of the inner zone. The boundary between the outer fibrous sclera and the cartilaginous sclera was irregular and obscured in myopic eyes. Spindle-shaped chondrocytes were seen to be in contact with each other. Thick collagen fibrils, usually seen only in the outer fibrous sclera, were present among the chondrocytes. Results of this morphological study suggest an increased proliferation of chondrocytes and active synthesis of extracellular matrix in visually deprived eyes. The elongation of the ocular axis that accompanies myopia is caused primarily by an active remodeling and differentiation in a restricted section of the posterior scleral cartilage. These facts indicate the posterior scleral cartilage may be more immature than cartilage in anterior and lateral segments.
类似的神经化学事件似乎参与了雏鸡和哺乳动物近视的发展。雏鸡孵化后的快速发育非常适合研究实验性近视。在本研究中，对2日龄雏鸡的一只眼睛剥夺形觉2周，然后通过免疫组织化学、光学显微镜和电子显微镜将其与未剥夺的对侧眼进行比较。所有剥夺眼均表现出高度屈光不正和眼球增大。在剥夺眼中，后软骨巩膜更厚，同一节段的纤维巩膜比对照眼更薄。巩膜形态学变化局限于后半球直径6-7毫米的中央区域（后极），进一步分为颞后和鼻后部分。剥夺巩膜最膨大的后软骨结构可分为内区和外区。内区有许多排列不均匀的软骨细胞，每个软骨细胞都有发达的颗粒内质网和高尔基体复合体，细胞表面非常不规则。在外区检测到大量S期细胞和同源细胞群。在外区最内侧区域和内区最外侧区域经常观察到肥大软骨细胞。近视眼中，外纤维巩膜和软骨巩膜之间的边界不规则且模糊。可见梭形软骨细胞相互接触。通常仅在外纤维巩膜中可见的粗大胶原纤维存在于软骨细胞之间。这项形态学研究结果表明，视觉剥夺眼的软骨细胞增殖增加，细胞外基质合成活跃。近视伴随的眼轴伸长主要是由后巩膜软骨受限节段的活跃重塑和分化引起的。这些事实表明，后巩膜软骨可能比前节和侧节的软骨更不成熟。
