Assis B M, Silva L A F, Lima C R O, Sant'Ana F J F, Santos G P, Vulcani V A S, Rabelo R E
Universidade Federal de Goiás, Regional Jataí, BR 364, Km 195, 75800-000, Jataí, Goiás, Brazil.
Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Campus Samambaia, 74690-900, Goiânia, Goiás, Brazil.
Anat Histol Embryol. 2017 Oct;46(5):456-463. doi: 10.1111/ahe.12290. Epub 2017 Aug 31.
The aim of this study was to describe the microstructure of the pigmented and depigmented hoof capsule of Girolando cattle by bi- and tridimensional microtomography and nanoindentation, analysing the possible relation between these findings and the susceptibility of such animals to podal diseases. To carry out the microtomography and the nanoindentation, duplicated samples were collected from the dorsal wall, abaxial wall and pre-bulbar sole of the hoof capsule. Material collection was performed in 40 medial digits of thoracic limbs and 40 lateral digits of pelvic limbs. The bidimensional microtomography showed that the dorsal wall of the thoracic and pelvic limbs presented higher density, followed by the abaxial wall, and finally by the sole, with the lowest density. Moreover, the hoof capsule of cows of Girolando breed is a compact, non-porous material, and constituted by extratubular and intratubular keratin. By the tridimensional microtomography, it was possible to measure the angles of the corneal tubules in relation to the periople and the claws in the different regions of the hoof capsule, which were 90° for the dorsal wall, 55° for the abaxial wall and 70° for the sole. The tridimensional microtomography also showed corneal tubules of different diameters: 17, 51, 85, 119 and 153 μm. The nanoindentation test, when performed in different regions of the hoof capsule, did not reveal significant difference of Vickers hardness in the evaluated areas. However, we verified a larger elastic module of these regions on the transversal cut of the corneal tubules compared to the longitudinal cut.
本研究的目的是通过二维和三维显微断层扫描以及纳米压痕技术描述吉罗兰多牛色素沉着和色素脱失蹄匣的微观结构，分析这些结果与此类动物对蹄部疾病易感性之间的可能关系。为了进行显微断层扫描和纳米压痕测试，从蹄匣的背壁、外壁和球节前足底采集了重复样本。材料采集在40个胸肢内侧趾和40个盆腔肢外侧趾上进行。二维显微断层扫描显示，胸肢和盆腔肢的背壁密度较高，其次是外壁，最后是足底，密度最低。此外，吉罗兰多品种奶牛的蹄匣是一种致密、无孔的材料，由管周和管内角蛋白构成。通过三维显微断层扫描，可以测量蹄匣不同区域角膜小管相对于蹄冠和蹄爪的角度，背壁为90°，外壁为55°，足底为70°。三维显微断层扫描还显示了不同直径的角膜小管：17、51、85、119和153μm。在蹄匣不同区域进行纳米压痕测试时，评估区域的维氏硬度没有显著差异。然而，我们发现与纵向切片相比，角膜小管横向切片上这些区域的弹性模量更大。
