Finnøy Andreas, Olstad Kristin, Lilledahl Magnus B
a Department of Physics , Norwegian University of Science and Technology (NTNU) , Trondheim , Norway.
b Norwegian University of Life Sciences, Faculty of Veterinary Medicine and Biosciences , Oslo , Norway.
Connect Tissue Res. 2016 Sep;57(5):374-87. doi: 10.1080/03008207.2016.1190348. Epub 2016 May 23.
The articular-epiphyseal cartilage complex (AECC) is responsible for the expansion of the bone ends and serves the function of the articular cartilage in juvenile mammals. Bundles of collagen fibrils surrounding cells were in the literature observed more frequently near the articular surface of the AECC. The articular surface, the perichondrium, and cartilage canals are interfaces where appositional growth of the AECC has been demonstrated. The current study aimed to evaluate the potential of second harmonic generation (SHG) to locate the collagen fibril bundles near the articular surface and to examine whether a comparable collagen fibril organization could be observed near the other interfaces of the AECC.
The study included the femoral condyle of four piglets aged 82-141 days. The forward and backward scattered SHG, and their ratio, was analyzed across the AECC using objectives with different numerical aperture. Two-photon-excited fluorescence was used to visualize cells.
A similar pattern of collagen fibril organization was observed near the articular surface, around cartilage canals, and adjacent to the perichondrium. The pattern consisted of a higher ratio of forward to backward scattered SHG that increased relative to the surrounding matrix at lower numerical aperture. This was interpreted to reflect collagen fibril bundles in the territorial matrix of cells in these areas.
The observed arrangement of collagen fibrils was suggested to be related to the presumed different growth activity in these areas and indicated that SHG may be used as an indirect and label-free marker for cartilage matrix growth.
关节骨骺软骨复合体（AECC）负责骨端的生长，并在幼年哺乳动物中发挥关节软骨的功能。文献中更频繁地观察到围绕细胞的胶原纤维束靠近AECC的关节表面。关节表面、软骨膜和软骨管是已证实AECC有附加生长的界面。本研究旨在评估二次谐波产生（SHG）定位关节表面附近胶原纤维束的潜力，并检查在AECC的其他界面附近是否能观察到类似的胶原纤维组织。
该研究包括4只年龄在82 - 141天的仔猪的股骨髁。使用具有不同数值孔径的物镜分析整个AECC的前向和后向散射SHG及其比率。双光子激发荧光用于观察细胞。
在关节表面附近、软骨管周围和软骨膜相邻处观察到类似的胶原纤维组织模式。该模式由前向散射SHG与后向散射SHG的较高比率组成，在较低数值孔径下相对于周围基质增加。这被解释为反映了这些区域细胞的领地基质中的胶原纤维束。
观察到的胶原纤维排列被认为与这些区域假定的不同生长活性有关，并表明SHG可作为软骨基质生长的间接且无标记的标志物。
