京都大学 大学院医学研究科 人間健康科学系専攻 病理学研究室（形態形成医療科学）

奥村さんの卒業研究がPLoS Oneに受諾されました。

ヒトの骨格形成は、保存しやすく、レントゲンでの解析が可能な骨化中、骨化後の解析がほとんどで、軟骨形成期の解析はほとんどされていません。今回、骨盤の軟骨形成期に着目し解析を進めました。

• CRL 12 -75 mm) の骨盤骨格における軟骨形成を検討し以下のTimeTableをえる
  • 腸骨、坐骨、および恥骨の軟骨化中心は、寛骨臼の周囲にCS18 で同時に出現し、後のステージで放射状に成長
  • 腸骨稜は CS20 で形成
  • 腸骨体は CS22 で円盤状
  • 仙腸関節は CS21で形成
  • 恥骨結合の関節接合、仙骨の関節柱の接続、寛骨臼への寛骨の 3 つの部分の Y 字型の接続はCS23 で形成
  • 坐骨と恥骨枝の接続は、胎児の初期に形成
  • 仙骨の中心での接続の程度は、標本間で異なる
• 成長率は腸骨が恥骨、坐骨に比べて大きい
• 小骨盤の骨盤入口の横方向および前後方向の長さ, 恥骨下の角度はCRLと相関しない。
• 軟骨構造は、骨構造の形態に影響を与えることを示唆

28. Okumura M, Ishikawa A, Aoyama T, Yamada S, Uwabe C, Imai H, Matsuda T, Yoneyama A, Takeda T, Takakuwa T, Cartilage Formation in the Pelvic Skeleton during the Embryonic and Early-Fetal Period, PLoS One 12(4): e0173852. https://doi.org/10.1371/journal. pone.0173852 [Open Access]

Abstract

The pelvic skeleton is formed via endochondral ossification. However, it is not known how the normal cartilage is formed before ossification occurs. Furthermore, the overall timeline of cartilage formation and the morphology of the cartilage in the pelvis are unclear. In this study, cartilage formation in the pelvic skeletons of 25 human fetuses (crown-rump length [CRL] = 11.9–75.0 mm) was observed using phase-contrast computed tomography and 7T magnetic resonance imaging. The chondrification center of the ilium, ischium, and pubis first appeared simultaneously at Carnegie stage (CS) 18, was located around the acetabulum, and grew radially in the later stage. The iliac crest formed at CS20 while the iliac body’s central part remained chondrified. The iliac body formed a discoid at CS22. The growth rate was greater in the ilium than in the sacrum-coccyx, pubis, and ischium. Connection and articulation formed in a limited period, while the sacroiliac joint formed at CS21. The articulation of the pubic symphysis, connection of the articular column in the sacrum, and Y-shape connection of the three parts of the hip bones to the acetabulum were observed at CS23; the connection of the ischium and pubic ramus was observed at the early-fetal stage. Furthermore, the degree of connection at the center of the sacrum varied among samples. Most of the pelvimetry data showed a high correlation with CRL. The transverse and antero-posterior lengths of the pelvic inlet of the lesser pelvis varied among samples (R² = 0.11). The subpubic angle also varied (65–90°) and was not correlated with CRL (R² = 0.22). Moreover, cartilaginous structure formation appeared to influence bone structure. This study provides valuable information regarding the morphogenesis of the pelvic structure.