Development and growth of the human fetal sacroiliac joint revisited: a comparison with the temporomandibular joint
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Kim, Ji Hyun
1
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Jin, Zhe-Wu
2
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Hayashi, Shogo
6
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Murakami, Gen
5
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Abe, Hiroshi
3
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Rodríguez-Vázquez, José Francisco
4
- 1 Department of Anatomy, Jeonbuk National University Medical School, Jeonju, Korea,
- 2 Department of Anatomy, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
- 3 Emeritus professor of Akita University School of Medicine, Akita, Japan
- 4 Department of Anatomy and Human Embryology, Institute of Embryology, Complutense University, Madrid, Spain
- 5 Division of Internal Medicine, Cupid Clinic, Iwamizawa, Japan
- 6 Department of Anatomy, Tokai University School of Medicine, Isehara, Japan
ISSN: 2093-3665, 2093-3673
Year of publication: 2023
Type: Article
More publications in: Anatomy & Cell Biology
Abstract
The human fetal sacroiliac joint (SIJ) is characterized by unequal development of the paired bones and delayed cavitation. Thus, during the long in utero period, the bony ilium becomes adjacent to the cartilaginous sacrum. This morphology 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.