Steele M A, Garcia F, Lowerison M, Gordon K, Metcalf J A, Hurtig M
Nutreco Canada Agresearch, Guelph, Ontario, Canada N1G 4T2.
Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
J Dairy Sci. 2014 Dec;97(12):7691-6. doi: 10.3168/jds.2014-8374. Epub 2014 Sep 26.
Rumen development in calves has been evaluated by measuring papillae length, width, and density using microscopy for over 50 yr. Although common in the literature, disadvantages to this method exist, such as large variations in rumen papillae size and shape, small numbers of total papillae being measured, and the time required. The objective of this study was to develop a more effective technique for assessing rumen papillae using micro-computed tomography (micro-CT) and to compare this technique with microscopy. Rumen tissue was collected from the ventral sac of 20 postweaned bull calves at 55 d of age, immediately fixed in 10% neutral buffered formalin for 48 h, and stored in 70% ethanol at 4°C before the contrast enhancement. After evaluation of contrast-enhancement protocols, it was determined that mercury chloride provided the most pronounced contrast for accurate micro-CT imaging based on relative density of the papillae. A 1-cm(2) tissue section from the ventral sac of all bull calves was tensioned on a rapid prototyped curved plastic holder and imaged at 4 5 μm resolution for 56 min using a GE Locus Explore micro-CT (General Electric, Milwaukee, WI). MicroView V2.2 software (General Electric) was used to create a 3-dimensional virtual model of the entire sample. The length and width of papillae were measured 3-dimensionally and compared with measurements of papillae under the light microscope taken from the same region. The length and width measurements using micro-CT (2.47 ± 0.12 and 0.55 ± 0.01 mm) compared with light microscope (2.96 ± 0.03 and 0.86 ± 0.01 mm) were significantly smaller. The difference may reflect a more accurate determination in the base of the rumen tissue with micro-CT or the specificity of mercury chloride to bind only to intact rumen tissue. The mean number of papillae per centimeter squared viewed using micro-CT was 128.5 ± 33.9 with a total surface area of 681.8 ± 112.4 mm(2) and volume of 156 mm(3) per sample. Micro-CT data demonstrated that surface area and volume are positively associated and that papillae length was negatively associated with papillae per centimeter squared and positively associated with total volume of tissue section. This study represents the first time that micro-CT has been being used to assess morphology of rumen tissue. Micro-CT has the potential to improve the accuracy and efficiency of rumen tissue measurements; however, more standardization of each factor involved in tissue preparation, imaging, and location of papillae measurements is required.
在超过50年的时间里，人们一直通过显微镜测量乳头长度、宽度和密度来评估犊牛的瘤胃发育情况。尽管这种方法在文献中很常见，但它存在一些缺点，比如瘤胃乳头大小和形状差异很大、测量的乳头总数较少以及所需时间较长。本研究的目的是开发一种使用微型计算机断层扫描（micro-CT）评估瘤胃乳头的更有效技术，并将该技术与显微镜检查进行比较。从20头55日龄断奶后的公牛犊的腹囊收集瘤胃组织，立即固定在10%中性缓冲福尔马林中48小时，并在增强对比之前储存在4°C的70%乙醇中。在评估了对比增强方案后，确定基于乳头的相对密度，氯化汞能为精确的微型计算机断层扫描成像提供最显著的对比。从所有公牛犊的腹囊取1平方厘米的组织切片，张紧在快速成型的弯曲塑料支架上，使用通用电气Locus Explore微型计算机断层扫描（通用电气，威斯康星州密尔沃基）以45微米分辨率成像56分钟。使用MicroView V2.2软件（通用电气）创建整个样本的三维虚拟模型。从三维测量乳头的长度和宽度，并与在同一区域的光学显微镜下测量的乳头尺寸进行比较。使用微型计算机断层扫描测量的长度和宽度（2.47±0.12和0.55±0.01毫米）与光学显微镜测量的结果（2.96±0.03和0.86±0.01毫米）相比明显更小。这种差异可能反映了微型计算机断层扫描对瘤胃组织基部的测定更准确，或者氯化汞仅与完整瘤胃组织结合的特异性。使用微型计算机断层扫描观察到的每平方厘米乳头平均数量为128.5±33.9，每个样本的总表面积为681.8±112.4平方毫米，体积为156立方毫米。微型计算机断层扫描数据表明表面积和体积呈正相关，乳头长度与每平方厘米乳头数量呈负相关，与组织切片总体积呈正相关。本研究是首次使用微型计算机断层扫描评估瘤胃组织形态。微型计算机断层扫描有潜力提高瘤胃组织测量的准确性和效率；然而，需要对组织制备、成像以及乳头测量位置所涉及的每个因素进行更多标准化。
