Gignac Paul M, Kley Nathan J
Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York; Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, Tulsa, Oklahoma.
J Exp Zool B Mol Dev Evol. 2014 May;322(3):166-76. doi: 10.1002/jez.b.22561. Epub 2014 Jan 30.
The now widespread use of non-destructive X-ray computed tomography (CT) and micro-CT (µCT) has greatly augmented our ability to comprehensively detail and quantify the internal hard-tissue anatomy of vertebrates. However, the utility of X-ray imaging for gaining similar insights into vertebrate soft-tissue anatomy has yet to be fully realized due to the naturally low X-ray absorption of non-mineralized tissues. In this study, we show how a wide diversity of soft-tissue structures within the vertebrate head-including muscles, glands, fat deposits, perichondria, dural venous sinuses, white and gray matter of the brain, as well as cranial nerves and associated ganglia-can be rapidly visualized in their natural relationships with extraordinary levels of detail using iodine-enhanced (i-e) µCT imaging. To date, Lugol's iodine solution (I2 KI) has been used as a contrast agent for µCT imaging of small invertebrates, vertebrate embryos, and certain isolated parts of larger, post-embryonic vertebrates. These previous studies have all yielded promising results, but visualization of soft tissues in smaller invertebrate and embryonic vertebrate specimens has generally been more complete than that for larger, post-embryonic vertebrates. Our research builds on these previous studies by using high-energy µCT together with more highly concentrated I2 KI solutions and longer staining times to optimize the imaging and differentiation of soft tissues within the heads of post-embryonic archosaurs (Alligator mississippiensis and Dromaius novaehollandiae). We systematically quantify the intensities of tissue staining, demonstrate the range of anatomical structures that can be visualized, and generate a partial three-dimensional reconstruction of alligator cephalic soft-tissue anatomy.
如今,非破坏性X射线计算机断层扫描(CT)和显微CT(µCT)的广泛应用极大地增强了我们全面详细描述和量化脊椎动物内部硬组织解剖结构的能力。然而,由于非矿化组织对X射线的自然吸收率较低,X射线成像在深入了解脊椎动物软组织解剖结构方面的效用尚未得到充分发挥。在本研究中,我们展示了如何使用碘增强(i-e)µCT成像,以极高的细节水平快速可视化脊椎动物头部内多种软组织结构,包括肌肉、腺体、脂肪沉积、软骨膜、硬脑膜静脉窦、脑白质和灰质,以及颅神经和相关神经节,及其自然的相互关系。迄今为止,卢戈氏碘溶液(I₂KI)已被用作小型无脊椎动物、脊椎动物胚胎以及较大的胚胎后脊椎动物某些分离部位µCT成像的造影剂。这些先前的研究均取得了有前景的结果,但小型无脊椎动物和胚胎脊椎动物标本中软组织的可视化通常比大型胚胎后脊椎动物更完整。我们的研究基于这些先前的研究,通过使用高能µCT以及更高浓度的I₂KI溶液和更长的染色时间,来优化胚胎后恐龙(密西西比鳄和鸸鹋)头部软组织的成像和区分。我们系统地量化了组织染色强度,展示了可可视化的解剖结构范围,并生成了短吻鳄头部软组织解剖结构的部分三维重建。