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西谷さん、鳥居さんの胎児心臓の解析がJAHAに掲載

西谷さんの修士論文、鳥居さんの卒業論文;胎児心臓のDT-MRIによる解析がJAHAに掲載されました。

  • 従来の報告より8週以上若い時期のヒトの心筋走行を高解像度DT-MRIデータを用いて検出しました。
  • ヒトの心筋の走行の配置、螺旋状の角度等は、成人とすでに同様であることから、心筋構築の青写真は胚子期末(CS20-23, GSA8W)には、すでに形成されていることをから明らかにしました。
  • データは古典的な心筋バンド説(心筋はひとつながりのバンド状のものが立体的に折り畳まれて形成されている)を否定しました。

本研究成果は、京都大学HP(トピックス)でも紹介されました。

ヒト胎児心臓の心筋線維方向を追跡 -受精後8週の心筋線維は成人と同じ配列をする-  外部リンク[京都大学HP(トピックス)]

2020/10/13 医療NEWSにて,ヒト胎児の心臓、受精後8週で心筋線維の配列が成人と同様であることが判明-京大ほか が紹介されました.

46. Nishitani S, Torii N, Imai H, Haraguchi R, Yamada S, Takakuwa T, Development of helical myofiber tracts in the human fetal heart: Analysis of myocardial fiber formation in the left ventricle from the late human embryonic period using diffusion tensor magnetic resonance imaging. Journal of the American Heart Association, 2020, 19(9) doi:10.1161/JAHA.120.016422

Abstract

Background

Detection of the fiber orientation pattern of the myocardium using diffusion tensor magnetic resonance imaging lags ≈12 weeks of gestational age (WGA) behind fetal myocardial remodeling with invasion by the developing coronary vasculature (8 WGA). We aimed to use diffusion tensor magnetic resonance imaging tractography to characterize the evolution of fiber architecture in the developing human heart from the later embryonic period.

Methods and Results

Twenty human specimens (8–24 WGA) from the Kyoto Collection of Human Embryos and Fetuses, including specimens from the embryonic period (Carnegie stages 20–23), were used. Diffusion tensor magnetic resonance imaging data were acquired with a 7T magnetic resonance system. Fractional anisotropy and helix angle were calculated using standard definitions. In all samples, the fibers ran helically in an organized pattern in both the left and right ventricles. A smooth transmural change in helix angle values (from positive to negative) was detected in all 16 directions of the ventricles. This feature was observed in almost all small (Carnegie stage 23) and large samples. A higher fractional anisotropy value was detected at the outer side of the anterior wall and septum at Carnegie stage 20 to 22, which spread around the ventricular wall at Carnegie stage 23 and in the early fetal samples (11–12 WGA). The fractional anisotropy value of the left ventricular walls decreased in samples with ≥13 WGA, which remained low (≈0.09) in larger samples.

Conclusions

From the human late embryonic period (from 8 WGA), the helix angle arrangement of the myocardium is comparable to that of the adult, indicating that the myocardial structure blueprint, organization, and integrity are already formed.

田中さん、坂本さんの卒業研究がPLoS ONEに掲載

田中さん、坂本さんの卒業研究がPLoS ONEに掲載されました。胎児期の上肢帯の形態形成、位置の変化について詳述しました。

  • CS18で、烏口骨と上腕骨頭とともに肩甲骨体部を最初に検出
  • 肩甲骨下角は尾側方向に拡大したが、頭側はほとんど位置をかえない
  • 肩甲骨は胎児期には独特な位置(椎体の前方から側方への移動)、向き( 内部、上方回転)を示す

46. Tanaka S, Sakamoto R, Kanahashi T, Yamada S, Imai H, Yoneyama A, Takakuwa T. Shoulder girdle formation and positioning during embryonic and early fetal human development. PLoS ONE 2020, 15(9): e0238225. https://doi.org/10.1371/journal.pone.0238225

Abstract

Positional information on the shoulder girdle (the clavicle and scapula) is important for a better understanding of the function of the upper limb in the locomotive system as well as its associated disease pathogenesis. However, such data are limited except for information on the axial position of the scapula. Here, we describe a three-dimensional reconstruction of the shoulder girdle including the clavicle and scapula, and its relationship to different landmarks in the body. Thirty-six human fetal specimens (crown-rump length range: 7.6–225 mm) from the Kyoto Collection were used for this study. The morphogenesis and three-dimensional position of the shoulder girdle were analyzed with phase-contrast X-ray computed tomography and magnetic resonance imaging. We first detected the scapula body along with the coracoid and humeral head at Carnegie stage 18; however, the connection between the body and coracoid was not confirmed at this stage. During development, all landmarks on the shoulder girdle remained at the same axial position except for the inferior angle, which implies that the scapula enlarged in the caudal direction and reached the adult axial position in the fetal period. The scapula body was rotated internally and in the upward direction at the initiation of morphogenesis, but in the fetal period the scapula body was different than that in the adult position. The shoulder girdle was located at the ventral side of the vertebrae at the time of initial morphogenesis, but changed its position to the lateral side of the vertebrae in the late embryonic and fetal periods. Such a unique position of the shoulder girdle may contribute to the stage-specific posture of the upper limb. Adequate internal and upward rotation of the scapula could help in reducing the shoulder width, thereby facilitating childbirth. The data presented in this study can be used as normal morphometric references for shoulder girdle evaluations in the embryonic and fetal periods.

藤井さんの博士論文がJ Anat に掲載

藤井さんの博士論文がJ Anatomy に受諾されました。

詳細な形態変化情報と正確な分岐次数を算出することにより、これまで明らかでなかった胚子期の気管支形成について新たな知見を与えました。

  • 胚子期後期までの気管支樹の形態形成をあきらかにした
  • 気管および大葉気管支の構造は、個人差を示さなかったが、それより末梢では個人差がみられた。
  • 右上葉気管支は、右中葉気管支と左上葉気管支の両方の生成後に形成されました。
  • 右中葉の分岐次数の​​中央値は、他の 4 葉と比較して有意に低い、
  • 右下葉の分岐次数の中央値は、左右の上葉の値よりも有意に大きい。
  • CS20 と CS23 の間で見つかったバリエーションはすべて、成人の肺でみられ、気管支樹のバリエーションが胚子期に発生し、生涯続く可能性を示唆

<博士審査会の概要>

<修士論文(村中)の概要>

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 Anatomy 2020, 237, 311-322. doi: 10.1111/joa.13199.

Abstract

A classical study has revealed the general growth of the bronchial tree and its variations up to Carnegie stage (CS) 19. In the present study, we extended the morphological analysis CS by CS until the end of the embryonic period (CS23). A total of 48 samples between CS15 and CS23 belonging to the Kyoto Collection were used to acquire imaging data by performing phase-contrast X-ray computed tomography. Three-dimensionally reconstructed bronchial trees revealed the timeline of morphogenesis during the embryonic period. Structures of the trachea and lobar bronchus showed no individual difference during the analyzed stages. The right superior lobar bronchus was formed after the generation of both the right middle lobar bronchus and the left superior lobar bronchus. The speed of formation of the segmental bronchi, sub-segmental bronchi, and further generation seemed to vary among individual samples. The distribution of the end-branch generation among five lobes was significantly different. The median branching generation value in the right middle lobe was significantly low compared with that of the other four lobes, whereas that of the right inferior lobe was significantly larger than that of both the right and left superior lobes. Variations found between CS20 and CS23 were all described in the human adult lung, indicating that variation in the bronchial tree may well arise during the embryonic period and continue throughout life. The data provided may contribute to a better understanding of bronchial tree formation during the human embryonic period.

大賀さんの卒業論文がCongenit Anomに掲載

大賀さんの卒業研究がCongenital Anomaliesに掲載されました。胚子期後期(CS21前後)にみられる後頚部浮腫について、リンパ管の形成との関連性を論じました。

  • 皮下浮腫およびくも膜下腔の拡大が後頚部浮腫 の原因
  • 頸静脈リンパ嚢は、第1頸椎と第4頸椎の間のレベルで両側に位置し、形状はピラミッド型、皮下組織およびくも膜下腔に接続されていない

 *同号の表紙にも採用されました。

Ohga A, Sakamoto R, Yamada S, Takakuwa T, Vesicular swelling in the cervical region with lymph sac formation in human embryos. Congenit Anom, 2020, 60, 62-67: 10.1111/cga.12339.

Abstract

Vesicular swelling in the cervical region (VSC) is occasionally observed among human embryos around Carnegie stage (CS) 21. However, its mechanism and significance in fetal development are unclear. The present study aimed to analyze the relation of development of VSC with jugular lymph sac (JLS) formation. Serial histological sections that were digitalized from 14 embryos at CS20 and CS21 stored at the Kyoto Collection were used for the analysis. Subcutaneous edema and enlargement of the subarachnoid space were found to cause VSC. No obvious abnormalities in cranial regions that may be related to the VSC were detected on histological sections. Three-dimensional reconstructions revealed the following: (a) the JLS was located bilaterally at the levels between the first and fourth cervical vertebrae; (b) the JLS was pyramidal in shape; and (c) no severe deformity and/or malformation was found in all samples. The JLS was not connected to the subcutaneous tissue and subarachnoid space in all samples. The mean volume of the JLS increased nine-times from CS20 (0.02 mm3 in VSC [−] group) to CS21 (0.18 mm3 in VSC [−] group). The mean volume of the JLS was comparable between the VSC [−] and VSC (+) groups at both CS20 and CS21. A moderate correlation was observed between VSCd and the mean volume of the JLS in both groups at CS20 (R2 = 0.75) and CS21 (R2 = 0.56). In conclusion, the dynamics of the lymphatic system at the cervical region may contribute to VSC observed around CS21. 

奥野さん、松林先生の研究がDevelopmental Dynamicsに掲載

奥野さんの卒業研究がDevelopmental Dynamicsに受諾されました。

  • 肋骨対の3次元座標を用いて主成分分析を行いました。
  • 各肋骨対の PC1 および PC2 値の位置は、発生に伴い適合曲線に沿って移動した、
  • PC1 と PC2 の変化は、近似曲線を形状の線形スケールとして使用する単一のパラメーターで表すことが可能
  • 形態形成時の肋骨の形態は少数の限られた因子で制御されている可能性を示した。(parsimonious modelの提唱)

40. Matsubayashi J, Okuno K, Fuji S, Ishizu K, Yamada S, Yoneyama A, Takakuwa T. Human embryonic ribs all progress through common morphological forms irrespective of their position on the axis, Dev Dyn 2019, 248, 1257-1263, doi: 10.1002/dvdy.107

parsimonious model

Abstract

Background

We aimed to analyze the morphogenesis of all ribs from 1st to 12th rib pairs plus vertebrae to compare their differences and features according to the position along the cranial-caudal axis during the human embryonic period.

Results

Rib pair formation was analyzed using high-resolution digitalized imaging data (n = 29) between Carnegie stage (CS) 18 and CS23 (corresponding to ED13-14 in mouse; HH29-35 in chick). A total of 348 rib pairs, from 1st to 12th rib pairs of each sample were subjected to Procrustes and principal component (PC) analyses. PC1 and PC2 accounted for 76.3% and 16.4% (total 92.7%) of the total variance, respectively, indicating that two components mainly accounted for the change in shape. The distribution of PC1 and PC2 values for each rib showed a “fishhook-like shape” upon fitting to a quartic equation. PC1 and PC2 value position for each rib pair moved along the fitted curve according to the development. Thus, the change in PC1 and PC2 could be expressed by a single parameter using a fitted curve as a linear scale for shape.

Conclusion

Human embryonic ribs all progress through common morphological forms irrespective of their position on the axis.

奥野さんの卒業論文がAnat Recに掲載

奥野さんの卒業論文がAnatomical Recordに掲載されました。

胚子期の位相CTを用いて、肋骨、脊椎上に座標を84点/標本とり、胸郭の形成の特徴を定量的に示しました。

  • CS17 に肋骨の軟骨形成が検出可能、胸腹部の背側から外側に拡大
  • 肋骨は、胸部を取り囲むように伸び、CS20 に上部と下部の胸郭領域に分化
  • 上部領域の対応する肋骨の端は、CS21 -CS23 の間に結合し胸骨形成する。
  • 最大幅の胸郭領域は、CS17 の 5 番目の肋骨対から CS23 の 9 番目の肋骨対に移動
  • 最大幅の位置に肝臓あり、最大深さの部位に心臓あり

Okuno K, Ishizu K, Matsubayashi J, Fujii S, Sakamoto R, Ishikawa A, Yamada S, Yoneyama A, Takakuwa T. Rib cage morphogenesis in the human embryo: A detailed three-dimensional analysis. Anat Rec 2019, 302, 2211-2223, doi: 10.1002/ar.24226

ABSTRACT

Formation of the skeletal structure in the human embryo has important consequences in terms of support, protection, and function of organs and other systems. We aimed to describe the formation of the rib cage during the embryonic period, in order to detect prominent features and identify the possible factors affecting rib cage morphology. We employed high-resolution digitized imaging data (n = 34) obtained in human embryos with Carnegie stage (CS) between 17 and 23. The rib cage became detectable as cartilage formation at CS17, expanding outward from the dorsal side of the chest-abdominal region. Ribs elongated progressively to surround the chest, differentiating into the upper and lower rib cage regions by CS20. The ends of corresponding ribs in the upper region elongated toward each other, leading to their joining and sternum formation between CS21 and CS23, while the lower region of the rib cage remained widely open. The rib cage area with the largest width shifted from the 5th rib pair at CS17 to the 9th pair at CS23. The depth of the rib cage was similar across the upper region at CS17, with the major portion remaining in the middle part after CS20. The heart was located beneath the rib pairs providing the largest depth, while the liver was located beneath the rib pairs providing the largest width. Formation of the sternum, development of spinal kyphosis, and organization of larger internal organs within the thoracic and abdominal cavity are possible factors affecting rib cage morphology. Anat Rec, 302:2211–2223, 2019.

腎臓の回転、移動についての論文がAnat Recに掲載

腎臓の回転、移動についての論文がAnat Recに受諾されました。

腎臓が発生時に上昇し回転することは教科書に書かれています。その動きを3Dでしっかり観察したこと、集合管尿路系の形成との関連で論じたことが特徴です。

  • 腎門の向きは、CS17 (34.4  度) と 18 (122.3度) の間で大幅に変化
  • 尿路樹の分岐数が CS17 での1.61 から CS18で3.20 に増加
  • 枝の数の増加は、後腎の成長と腎門の方向に影響を与えた。

石山さんの修士の仕事に石川さんがデータを追加してくれました。

37. Ishiyama H, Ishikawa A, Imai H, Matsuda T, Yoneyama A, Yamada S, Takakuwa T. Spatial relationship between the metanephros and adjacent organs according to the Carnegie stage of development. Anat Rec 2019. 302, 1887-2104. DOI: 10.1002/ar.24103

ABSTRACT

The morphological changes in the metanephros and its spatial relationship to the adjacent organs was evaluated based on the Carnegie stages (CSs) from 14 through 23. The imaging modalities used included magnetic resonance imaging (N = 4), phase-contrast X-ray computed tomography (N = 11), and serial histological sections (N = 40), supplemented by three-dimensional image reconstruction. The orientation of the hilus of the metanephros changed significantly between CS17 (34.4 ± 13.7 degrees) and 18 (122.3 ± 38.1 degrees), with an increase in the number of branches of the urinary collecting system, from 1.61 ± 0.42 at CS17 to 3.20 ± 0.35 at CS18. This increase in the number of branches influenced the growth of the metanephros and the orientation of its hilus. The right and left metanephroses were in proximity throughout the embryonic period. The local maximum interpole distances were observed at CS18 (0.87 ± 0.11 mm for the upper and 0.50 ± 0.25 mm for the lower pole). Mesenchymal tissue was observed between the metanephros and iliac arteries, as well as between the right and left metanephros. Throughout development, the position of the lower pole of the metanephros remained adjacent to the aortic bifurcation. The position of the upper pole, referenced with respect to the aortic bifurcation, increased by >2.0 mm, reflecting the longitudinal growth of the metanephros. Our findings provide a detailed description of the morphogenesis of the metanephros and of its hilus, which might contribute to our understanding of congenital malformations and malpositions of the kidneys. 

肝臓形成不全でも生理的臍帯ヘルニアは起きる: Anat Recに掲載

胚子期、消化管は大きい肝臓に押し出され臍帯内に脱出すると言われています。この機序は、発生の大家Mall博士が19世紀末に提唱し、今多くの教科書に記されています。そうしたら、肝臓形成不全で肝臓が小さい胚子、肝臓がない胚子ではどうなのでしょうか? 

  • 本研究では、消化管臍帯ヘルニアが肝臓の容積に関係なく発生することを示す標本を複数提示することで、発生の大家の提示した説に異議を唱えました。

Kanahashi T, Yamada S, Yoneyama A, Takakuwa T. Relationship Between Physiological Umbilical Herniation and Liver Morphogenesis During the Human Embryonic Period: A Morphological and Morphometric Study. Anat Rec 2019, 302, 1968-1976. doi: 10.1002/ar.24149.

肝臓無形成でも生理的臍帯ヘルニアがみられる

ABSTRACT

It is widely hypothesized that physiological umbilical herniation (PUH) in humans occurs, because the liver occupies a large space in the abdominal cavity, which pushes the intestine into the extraembryonic coelom during the embryonic period. We have recently shown the presence of the intestinal loop in the extraembryonic coelom in embryos with liver malformation. Here, we analyzed the relationship between the liver and the PUH at Carnegie stage 21 of four embryos with liver malformation, including two with hypogenesis (HY1, HY2) and two with agenesis (AG1, AG2), using phase-contrast X-ray computed tomography and compared them with two control embryos. The intestinal loop morphology in the malformed embryos differed from that in the control embryos, except in HY1. The length of the digestive tract in the extraembryonic coelom of the embryos with liver malformation was similar to or longer than that of the controls. The rate of intestinal loop lengthening in the extraembryonic coelom compared with that of the total digestive tract in all embryos with liver malformation was similar to or higher than that of the controls. The estimated total abdominal cavity volume in the embryos with liver malformation was considerably smaller than that of the controls, while the intestinal volume was similar. The cardia and proximal portion of the pancreas connecting to the duodenum were located at almost identical positions in all the embryos, whereas other parts of the upper digestive tract deviated in the embryos with abnormal livers. Thus, our results provided evidence that PUH occurred independently of liver volume.