Kim Ji Hyun, Jin Zhe-Wu, Hayashi Shogo, Murakami Gen, Abe Hiroshi, Rodríguez-Vázquez José Francisco
Department of Anatomy, Jeonbuk National University Medical School, Jeonju, Korea.
Department of Anatomy, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China.
Anat Cell Biol. 2023 Jun 30;56(2):252-258. doi: 10.5115/acb.22.189. Epub 2023 Feb 15.
The human fetal sacroiliac joint (SIJ) is characterized by unequal development of the paired bones and delayed cavitation. Thus, during the long period, the bony ilium becomes adjacent to the cartilaginous sacrum. This mor-phology may be analogous to that of the temporomandibular joint (TMJ). We examined horizontal histological sections of 24 fetuses at 10-30 weeks and compared the timing and sequences of joint cartilage development, cavitation, and ossification of the ilium. We also examined histological sections of the TMJ and humeroradial joint, because these also contain a disk or disk-like structure. In the ilium, endochondral ossification started in the anterior side of the SIJ, extended posteriorly and reached the joint at 12 weeks GA, and then extended over the joint at 15 weeks GA. Likewise, the joint cartilage appeared at the anterior end of the future SIJ at 12 weeks GA, and extended along the bony ilium posteriorly to cover the entire SIJ at 26 weeks GA. The cavitation started at 15 weeks GA. Therefore, joint cartilage development seemed to follow the ossification of the ilium by extending along the SIJ, and cavitation then occurred. This sequence "ossification, followed by joint cartilage formation, and then cavitation" did not occur in the TMJ or humeroradial joint. The TMJ had a periosteum-like membrane that covered the joint surface, but the humeroradial joint did not. After muscle contraction starts, it is likely that the mechanical stress from the bony ilium induces development of joint cartilage.
人类胎儿骶髂关节（SIJ）的特点是成对骨骼发育不均且空化延迟。因此，在很长一段时间内，骨髂骨与软骨骶骨相邻。这种形态可能类似于颞下颌关节（TMJ）。我们检查了24例10 - 30周胎儿的水平组织切片，并比较了关节软骨发育、空化和髂骨骨化的时间和顺序。我们还检查了颞下颌关节和肱桡关节的组织切片，因为这些关节也包含盘状或类似盘状的结构。在髂骨中，软骨内骨化始于骶髂关节的前侧，向后延伸并在孕12周时到达关节，然后在孕15周时延伸至关节上方。同样，关节软骨在孕12周时出现在未来骶髂关节的前端，并沿骨髂骨向后延伸，在孕26周时覆盖整个骶髂关节。空化始于孕15周。因此，关节软骨的发育似乎是沿着骶髂关节延伸，跟随髂骨的骨化，然后发生空化。这种“骨化，接着是关节软骨形成，然后是空化”的顺序在颞下颌关节或肱桡关节中并未出现。颞下颌关节有一层类似骨膜的膜覆盖关节表面，但肱桡关节没有。肌肉收缩开始后，来自骨髂骨的机械应力可能会诱导关节软骨的发育。
