Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853, USA.
Anat Rec (Hoboken). 2011 Jan;294(1):1-10. doi: 10.1002/ar.21336.
Embryonic development is a remarkably complex and rapidly evolving morphogenetic process. Although many of the early patterning events have been well described, understanding the anatomical changes at later stages where clinically relevant malformations are more likely to be survivable has been limited by the lack of quantitative 3D imaging tools. Microcomputed tomography (Micro-CT) has emerged as a powerful tool for embryonic imaging, but a quantitative analysis of organ and tissue growth has not been conducted. In this study, we present a simple method for acquiring highly detailed, quantitative 3D datasets of embryonic chicks with Micro-CT. Embryos between 4 and 12 days (HH23 and HH40) were labeled with osmium tetroxide (OT), which revealed highly detailed soft tissue anatomy when scanned at 25 μm resolution. We demonstrate tissue boundary and inter-tissue contrast fidelity in virtual 2D sections are quantitatively and qualitatively similar to those of histological sections. We then establish mathematical relationships for the volumetric growth of heart, limb, eye, and brain during this period of development. We show that some organs exhibit constant exponential growth (eye and heart), whereas others contained multiple phases of growth (forebrain and limb). Furthermore, we show that cardiac myocardial volumetric growth differs in a time and chamber specific manner. These results demonstrate Micro-CT is a powerful technique for quantitative imaging of embryonic growth. The data presented here establish baselines from which to compare the effects of genetic or experimental perturbations. Quantifying subtle differences in morphogenesis is increasingly important as research focuses on localized and conditional effects.
胚胎发育是一个非常复杂和快速进化的形态发生过程。尽管许多早期的模式形成事件已经得到了很好的描述，但是对于临床上更有可能存活的后期阶段的解剖学变化的理解，由于缺乏定量的 3D 成像工具而受到限制。微计算机断层扫描（Micro-CT）已成为胚胎成像的有力工具，但对器官和组织生长的定量分析尚未进行。在这项研究中，我们提出了一种使用 Micro-CT 获得具有高度详细的定量 3D 数据集的胚胎小鸡的简单方法。胚胎在 4 到 12 天（HH23 和 HH40）之间用锇四氧化物（OT）标记，在以 25μm 分辨率扫描时，揭示了高度详细的软组织解剖结构。我们证明了虚拟 2D 切片中的组织边界和组织间对比度保真度在定量和定性上与组织学切片相似。然后，我们建立了在此期间心脏、肢体、眼睛和大脑体积生长的数学关系。我们表明，一些器官表现出恒定的指数生长（眼睛和心脏），而其他器官包含多个生长阶段（前脑和肢体）。此外，我们还表明，心脏心肌体积生长具有时间和腔室特异性。这些结果表明 Micro-CT 是一种用于定量成像胚胎生长的强大技术。这里提供的数据建立了基线，可用于比较遗传或实验干扰的影响。量化形态发生的细微差异变得越来越重要，因为研究重点是局部和条件效应。
