Visual Neuroscience and Molecular Biology Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, Wales, CF24 4LU, UK.
Exp Eye Res. 2009 Oct;89(4):511-21. doi: 10.1016/j.exer.2009.05.014. Epub 2009 Jun 18.
Magnetic resonance imaging (MRI) is a powerful tool for generating 3-dimensional structural and functional image data. MRI has already proven valuable in creating atlases of mouse and quail development. Here, we have exploited high resolution MRI to determine the parameters necessary to acquire images of the chick embryo eye. Using a 9.4 Tesla (400 MHz) high field ultra-shielded and refrigerated magnet (Bruker), MRI was carried out on paraformaldehyde-fixed chick embryos or heads at E4, E6, E8, and E10. Image data were processed using established and custom packages (MRICro, ImageJ, ParaVision, Bruker and mri3dX). Voxel dimensions ranged from 62.5 microm to 117.2 microm. We subsequently used the images obtained from the MRI data in order to make precise measurements of chick embryo eye surface area, volume and axial length from E4 to E10. MRI was validated for accurate sizing of ocular tissue features by direct comparison with previously published literature. Furthermore, we demonstrate the utility of high resolution MRI for making accurate measurements of morphological changes due to experimental manipulation of chick eye development, thereby facilitating a better understanding of the effects on chick embryo eye development and growth of such manipulations. Chondroitin sulphate or heparin were microinjected into the vitreous cavity of the right eyes of each of 3 embryos at E5. At E10, embryos were fixed and various eye parameters (volume, surface area, axial length and equatorial diameter) were determined using MRI and normalised with respect to the un-injected left eyes. Statistically significant alterations in eye volume (p < 0.05; increases with chondroitin sulphate and decreases with heparin) and changes in vitreous homogeneity were observed in embryos following microinjection of glycosaminoglycans. Furthermore, in the heparin-injected eyes, significant disturbances at the vitreo-retinal boundary were observed as well as retinal folding and detachment confirming histological observations. These data reveal the utility and superiority of MRI for producing images enabling quantification of experimentally induced changes in eye volume and structure. The results indicate that MRI is an important tool that could become a routine approach for rapid and sensitive phenotypic analysis of normal chick ocular development and morphology as well as potentially the effects of surgical or genetic manipulations of chick embryo eyes in live embryos in ovo.
磁共振成像（MRI）是生成三维结构和功能图像数据的强大工具。MRI 在创建小鼠和鹌鹑发育图谱方面已经证明了其价值。在这里，我们利用高分辨率 MRI 来确定获取鸡胚眼睛图像所需的参数。使用 9.4 特斯拉（400MHz）高场超屏蔽和冷却磁体（Bruker），在 E4、E6、E8 和 E10 对戊二醛固定的鸡胚或头部进行 MRI 扫描。使用已建立的和自定义的软件包（MRICro、ImageJ、ParaVision、Bruker 和 mri3dX）处理图像数据。体素尺寸范围为 62.5 微米至 117.2 微米。随后，我们使用从 MRI 数据中获得的图像，以便从 E4 到 E10 对鸡胚眼睛表面积、体积和轴向长度进行精确测量。通过与先前发表的文献进行直接比较，MRI 验证了对眼部组织特征进行准确测量的准确性。此外，我们还展示了高分辨率 MRI 用于对鸡眼发育实验操作引起的形态变化进行精确测量的实用性，从而更好地理解此类操作对鸡胚眼发育和生长的影响。在 E5 时，将软骨素硫酸盐或肝素微注射到 3 个胚胎的右眼玻璃体腔中。在 E10 时，将胚胎固定，并使用 MRI 确定各种眼睛参数（体积、表面积、轴向长度和赤道直径），并相对于未注射的左眼进行归一化。在注射糖胺聚糖后，观察到眼睛体积（p<0.05；软骨素硫酸盐增加，肝素减少）和玻璃体均匀性变化的统计学显著改变。此外，在肝素注射的眼睛中，观察到玻璃体视网膜边界处存在明显干扰，以及视网膜折叠和脱离，证实了组织学观察结果。这些数据表明 MRI 是一种强大的工具，可用于产生图像，从而定量分析眼部体积和结构的实验诱导变化。结果表明，MRI 是一种重要的工具，它可以成为一种快速而敏感的鸡眼部正常发育和形态表型分析的常规方法，以及对鸡胚眼睛进行手术或遗传操作的活体胚胎中潜在影响的方法。
