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
骨盤（胎児期初期）
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.
44. Fujii S, Muranaka T, Matsubayash J, Yamada S, Yoneyama A, Takakuwa T. The bronchial tree of the human embryo: an analysis of variations in the bronchial segments. J Anat 2020, 237, 311-322. doi: 10.1111/joa.13199.
48. Fujii S, Muranaka T, Matsubayashi J, Yamada S, Yoneyama A, Takakuwa T. Bronchial tree of the human embryo: categorization of the branching mode as monopodial and dipodial, PLoS One 16; e0245558, 2021, https://doi.org/10.1371/journal.pone.0245558
Gyrification index (GI) of brain slices in a left lateral view of the brain in a 1409g fetus. The line graph above the brain shows the GI of each slice below it. The GI of the whole hemisphere changed in the rostro-caudal dimension. Several maxima of the GI curve appeared in relation to gross landmarks. Further details can be seen in the article by Yoshida et al. in this issue.
27. Yoshida R, Koichi Ishizu K, Yamada S, Chigako Uwabe C, Okada T, Togashi K, Takakuwa T, The dynamics of gyrification in the human cerebral cortex during development, Congenit Anom, 57 (1) 8-14, 2017, DOI: 10.1111/cga.12179, 10.1111/cga.12181
Abstract
This study quantitatively characterized cortical gyrus folding over human neocortical development by calculating the gyrification index (GI) in 22 human fetal specimens from 16 to 40 weeks with magnetic resonance imaging data. GI values remained constant at approximately 1.0 until the fetal specimens reached 500 g body weight and 200 mm crown-rump length (CRL), respectively, and then increased in correlation with the body weight and CRL. The rostrocaudal GI distribution in the cerebral cortex revealed a correspondence of GI peaks with indentations of early-generated primary sulci at 21 weeks of gestation and more frequently increased GI values in the parieto-occipital region than in the fronto-temporal region at 31 and 40 weeks of gestation. These results provide a quantitative reference set for gyrification in normal human cortical development, which may help reveal the mechanism of neurodevelopmental disorders.
