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腎臓の高さの左右差についてがCongenital Anomaliesに受諾

腎臓の高さの左右差についてがCongenital Anomaliesに受諾されました。

胚子期の腎臓の上昇、回転についてはこれまでよく知られていましたが、腎臓の高さの左右差については不明でした。本研究では、胚子期に左右腎臓の高さに違いはなく、ともに上昇すること、胎児期初期になると右側が左側よりも高くなることを示しました。胎児期の腎臓上昇の様子は、胚子期とは傾向が異なり別の機序を考える必要があります。

Ishiyama-Takara H, Matsubayashi J, Yamada S, Tetsuya Takakuwa T, Height difference between the right and left metanephroi during early human fetal development, Congenit Anom 2024, in press.

岩佐さんの論文がCongenit Anomに掲載

岩佐さんの錐体筋の形成についての論文がCongenit Anomに受諾されました。雑誌の表紙に採用されました。

錐体筋(PM)と内転筋群

Iwasa Y, Kanahashi T, Imai H, Otani H, Yamada S, Takakuwa T, Pyramidalis muscle formation during human embryonic and early fetal periods, Congenit Anom 2024, 64, 32-39, DOI: 10.1111/cga.12551

錐体筋という腹壁前壁下部にある筋肉の形成について検討しました。

表紙に採用されました。https://doi.org/10.1111/cga.12522

  • 錐体筋は、前腹壁にある一対の小さな三角形の、役割の不明な筋
  • 高分解能磁気共鳴イメージングを用いて、錐体筋がいつ出現したか、その特徴は何かを明らかにすることを目的とした
  • CS18―23までの14個の胚子、59個の胎児(CRL:39.5-185.0mm)を選択した。
  • 錐体筋の形成は胚子期後期(CS20ごろ)にみられ、胎児期初期における錐体筋の頻度、左右差、性差、空間的位置は成体と同様であった。

The pyramidalis muscle (PM) is a paired small triangular muscle of the anterior abdominal wall, the physiological significance of which remains unclear. Recent studies have failed to detect this muscle during the embryonic period. Hence, the present study aimed to determine when PM emerged and reveal its features using high-resolution magnetic resonance imaging. Fourteen embryos between Carnegie stage (CS)18 and CS23 and 59 fetuses (crown-rump length: 39.5–185.0 mm) were selected for this study. The PM was first detected in one of the three samples at CS20. It was detected in five of the seven samples (71.4%) between CS21 and CS23. Forty-eight samples (81.4%) at early fetal period had PMs on both the right and left sides, and three (5.1%) had that only on the right side. Eight samples (13.6%) had no PMs. No side-differences or sexual dimorphisms were detected. The PM length was larger than the width in most samples, although the length/width ratio varied among the samples. The PM/rectus abdominis muscle length and PM/umbilicus-pubic symphysis length ratios were almost constant, irrespective of the crown-rump length. The PM is located ventrally inferior to the rectus abdominis and closer to the medial muscle groups of the lower limb than the rectus abdominis. The present study demonstrated that PM formation occurred in the late embryonic period, and that the frequency, side differences, sex dimorphism, and spatial position of the PM in the early fetal period were similar to those in adults.

磯谷さんの修士論文がAnatomical Recordに受諾

磯谷さんの修士論文がAnatomical Recordに受諾されました。

胎児循環に特有の胎盤から心臓にむかう静脈路(臍帯静脈、門脈洞、静脈管、下大静脈)について、領域による特徴を高解像度デジタルデータ(MRI, CT)から得られた立体再構成像と組織像を用いて検討しました。

  • 胎児循環に特有の胎盤から心臓にむかう静脈路(臍帯静脈、門脈洞、静脈管、下大静脈)について領域ごとの特徴を検討
  • 胚子期から胎児期初期の29個の標本を高解像度デジタル画像化のために選択し、18個の胚を組織学的解析のために選択した。
  • 領域による特徴を高解像度デジタルデータ(MRI, CT)から得られた立体再構成像と組織像を用いて検討し明らかにした。

Isotani N, Kanahashi T, Imai H, Yoneyama A, Yamada S, Takakuwa T. Regional differences in the umbilical vein and ductus venosus at different stages of normal human development. Anat Rec, 2024, in press. DOI:10.1002/ar.25421

During the fetal period, oxygenated blood from the placenta flows through the umbilical vein (UV), portal sinus, ductus venosus (DV), and inferior vena cava (IVC) to the heart. This venous route varies regionally in many aspects. Herein, we sought to characterize the venous route’s morphological features and regional differences during embryonic and early-fetal periods. Twenty-nine specimens were selected for high-resolution digitized imaging; 18 embryos were chosen for histological analysis. The venous route showed a primitive, large, S-shaped curved morphology with regional narrowing and dilation at Carnegie stage (CS) 15. Regional differences in vessel-wall differentiation became apparent from approximately CS20. The vessel wall was poorly developed in most DV parts; local vessel-wall thickness at the inlet was first detected at CS20. The lumen of the venous route changed from a non-uniform shape to a relatively round and uniform morphology after CS21. During the early-fetal period, two large bends were observed around the passage of the umbilical ring and at the inlet of the liver. The length ratio of the extrahepatic UV to the total venous route increased. The sectional area gradually increased during embryonic development, whereas differences in sectional area between the DV, UV, and IVC became more pronounced in the early-fetal period. Furthermore, differences in the sectional area between the narrowest part of the DV and other hepatic veins and the transverse sinus became more pronounced. In summary, the present study described morphological, morphometric, and histological changes in the venous route throughout embryonic and early-fetal development, clarifying regional characteristics.

石田かのんさんの修士論文がCells Tissues Organsに受諾

石田かのんさんの修士論文がCells Tissues Organsに受諾されました。

膝関節の後半月大腿靭帯(pMFL)は、膝関節安定への寄与や円盤状外側半月板(DLM)との関連が報告されていますが、健常な膝におけるその発生過程は調査されていません。本研究では、pMFLの形成について、ラットを対象に、組織切片、EFIC等を用いて検討しました。理学療法学講座の青山先生、谷間先生との共同研究です。

  • EFIC画像から作成した3次元再構成画像を用いて、ラットの膝関節における後半月板靭帯の発達を解析し、他の膝関節構成要素との関係を検討。
  • E16-21日のWistarラット胚の膝関節を対象。
  • pMFLはE17から観察され、成熟ラットと同様にすべての発育段階で大腿骨内側顆と外側半月板に付着
  • pMFLと膝関節周囲の構成要素は、発生初期から位置関係を維持したまま発達していると考えられる。

Ishida K, Ishikawa A, Yamada S, Takakuwa T, Aoyama T, Three-dimensional imaging analysis of the developmental process of posterior meniscofemoral ligaments in rat embryos. Cells Tissues Organs 2024, in press, , DOI: 10.1159/000536108

The posterior meniscofemoral ligament (pMFL) of knee joint is a ligament that runs posterior to the posterior cruciate ligament (PCL) and it is known that the height of the pMFL attachment site causes meniscus avulsion. Therefore, understanding the three-dimensional (3D) structure of the pMFL attachment site is essential to better understand the pathogenesis of meniscus disorders. However, the developmental process of pMFL has not been well investigated. The purpose of this study was to analyze pMFL development in rat knee jointsusing 3D reconstructed images produced from episcopic fluorescence image capture (EFIC) images and examine its relationship with other knee joint components. Knee joints of Wistar rat embryos between embryonic day (E) 16 and E21 were observed with HE stained tissues. Serial EFIC images of the hindlimbs of E17-E21 were respectively captured, from which 3Dimages were reconstructed and the features of pMFL structure: length and angle, were measured. Besides, the chronological volume changes and the volume ratio of the knee joint components compared to E17 were calculated to identify the differences in growth by components. pMFL was observed from E17 and was attached to the medial femoral condyle and lateral meniscus at all developmental stages, as in mature rats. The lack of marked variation in the attachment site and angle of the pMFL with the developmental stage indicates that the pMFL and surrounding knee joint components developed while maintaining their positional relationship from the onset of development. Current results may support to congenital etiology of meniscus disorder.

藤井さんの論文がJ Anatomyに掲載

  • 比較解剖学的研究で哺乳類の気管支樹の基本モデルとして提案されている左右の気管支の対称性が、ヒトの胎児の気管支樹に当てはまるかどうかを検討
  • ヒト成人の気管支分岐構造の原型が胎児期に形成され、維持されることを実証
  • すべての肺葉気管支、B6、B8、B9、および B10 の亜分節気管支の形態および分岐位置は、遺伝的に決定される可能性がある
  • B10 の亜分節気管支以降の末梢枝では個々の胚間に共通の構造は見つからず、この領域での枝形成は遺伝的要因よりも環境的要因により影響されることが示唆された

Fujii S, Muranaka T, Matsubayashi J, Yamada S, Yoneyama A, Takakuwa T. Bronchial tree of the human embryo: Examination based on a mammalian model. J Anatomy 2024, 244, 159-169 http://doi.org/10.1111/joa.13946 .

The symmetry of right and left bronchi, proposed in a previous comparative anatomical study as the basic model of the mammalian bronchial tree, was examined to determine if it applied to the embryonic human bronchial tree. Imaging data of 41 human embryo specimens at Carnegie stage (CS) 16–23 (equivalent to 6–8 weeks after fertilization) belonging to the Kyoto collection were obtained using phase-contrast X-ray computed tomography. Three-dimensional bronchial trees were then reconstructed from these images. Bronchi branching from both main bronchi were labeled as dorsal, ventral, medial, or lateral systems based on the branching position with numbering starting cranially. The length from the tracheal bifurcation to the branching point of the labeled bronchus was measured, and the right-to-left ratio of the same labeled bronchus in both lungs was calculated. In both lungs, the human embryonic bronchial tree showed symmetry with an alternating pattern of dorsal and lateral systems up to segmental bronchus B9 as the basic shape, with a more peripheral variation. This pattern is similar to that described in adult human lungs. Bronchial length increased with the CS in all labeled bronchi, whereas the right-to-left ratio was constant at approximately 1.0. The data demonstrated that the prototype of the human adult bronchial branching structure is formed and maintained in the embryonic stage. The morphology and branching position of all lobar bronchi and B6, B8, B9, and the subsegmental bronchus of B10 may be genetically determined. On the other hand, no common structures between individual embryos were found in the peripheral branches after the subsegmental bronchus of B10, suggesting that branch formation in this region is influenced more by environmental factors than genetic factors.

福井さんの修士論文がJ Anatomyに掲載

福井さんの修士論文がJ Anatomyに受諾されました。ヒト胎児期初期の左房の形成を肺静脈のとりこみと左心耳の形成を中心に解析しました。

  • 23例の胚子期、19例の胎児期初期標本を選択した。
  • 高分解能イメージング(位相CTとMRI)から三次元心臓画像を再構成し、左心耳を含む肺静脈と左心房を形態学的および定量的に評価した。
  • 心臓の背側中膜結合が退縮したとき(CS18以降)、心膜折り返しの位置が2つの肺静脈(右肺静脈と左肺静脈)と4つの肺静脈でほぼ同時に決定された。
  • 左心房のひだが体部と静脈成分の接合部に存在することが確認された。
  • 左心房の肺静脈由来の静脈成分は成長に比例して増加することが示された。肺静脈成分と左心房体との接合部は徐々に目立たなくなったが、観察された初期胎児期の終わりにはまだ認識可能であった。

Fukui N, Toru KanahashiT, MatsubayashiJ, ImaiH, YoneyamaA, OtaniH, YamadaS, Takakuwa T. Morphogenesis of the pulmonary vein and left atrial appendage in human embryos and early fetuses. J Anatomy 2024, 244, 142-158, in press, https://doi.org/10.1111/joa.13941

Abstract

The left atrium wall has several origins, including the body, appendage, septum, atrial–ventricular canal, posterior wall, and venous component. Here, we describe the morphogenesis of left atrium based on high-resolution imaging (phase-contrast X-ray computed tomography and magnetic resonance imaging). Twenty-three human embryos and 19 fetuses were selected for this study. Three-dimensional cardiac images were reconstructed, and the pulmonary veins and left atrium, including the left atrial appendage, were evaluated morphologically and quantitatively. The positions of the pericardial reflections were used as landmarks for the border of the pericardial cavity. The common pulmonary vein was observed in three specimens at Carnegie stage 17–18. The pericardium was detected at the four pulmonary veins (left superior, left inferior, right superior, and right inferior pulmonary veins) at one specimen at Carnegie stage 18 and all larger specimens, except the four samples. Our results suggest that the position of the pericardial reflections was determined at two pulmonary veins (right and left pulmonary vein) and four pulmonary veins almost simultaneously when the dorsal mesocardial connection between the embryo and heart regressed. The magnetic resonance images and reconstructed heart cavity images confirmed that the left atrium folds were present at the junction between the body and venous component. Three-dimensional reconstruction showed that the four pulmonary veins entered the dorsal left atrium tangentially from the lateral to the medial direction. More specifically, the right pulmonary veins entered at a greater angle than the left pulmonary veins. The distance between the superior and inferior pulmonary veins was shorter than that between the left and right pulmonary veins. Three-dimensional reconstruction showed that the venous component increased proportionally with growth. No noticeable differences to discriminate between the right and left parts of the venous component emerged, while the junction between the venous component and body gradually became inconspicuous but was still recognizable by the end of the observed early fetal period. The left superior pulmonary vein had the smallest cross-sectional area and most flattened shape, whereas the other three were similar in area and shape. The left atrial appendage had a large volume in the center and extended to the periphery as a lobe-like structure. The left atrial appendage orifice increased in the area and tended to become flatter with growth. The whole left atrium volume^(1/3) increased almost proportionally with growth, parallel to the whole heart volume. This study provided a three-dimensional and quantitative description of the developmental process of left atrium, comprising the venous component and left atrial appendage formation, from the late embryonic to the early fetal stages.

胚子期の股関節の肢位についての論文がPLoS Oneに掲載

胚子期の股関節の肢位についての論文がPLoS Oneに掲載されました。熊野くんが卒業研究で行ったデータに、胚子期の標本のデータを追加し解析しました。大腿骨(股関節)の肢位を正確に測定し、下肢の発達の時間軸を確立することを目的とした論文です。

  • CS19-23の胚子期157体と胎児(CRL:37.2-225mm)18体のMRI画像を対象とした。
  • 下肢と骨盤の選択された8つのランドマークの3次元座標を用いて大腿骨の肢位を計測。
  • 胚子期には、股関節の屈曲、外転、側転の3つの姿勢パラメータが互いに線形相関を示し、各段階の大腿骨姿勢は3次元的に一定で、成長に応じて緩やかで滑らかな変化を示すことが示唆された。

60. Takakuwa T, Saizonou MA, Fujii S, Kumano Y, Ishikawa A, Aoyama T, Imai H, Yamada S, Kanahashi T. Femoral posture during embryonic and early fetal development: An analysis using landmarks on the cartilaginous skeletons of ex vivo human specimens. PLOS one, 2023, 18(5): e0285190. https://doi.org/10.1371/journal.pone.0285190.

Abstract

The pre-axial border medially moves between the fetal and early postnatal periods, and the foot sole can be placed on the ground. Nonetheless, the precise timeline when this posture is achieved remains poorly understood. The hip joint is the most freely movable joint in the lower limbs and largely determines the lower-limb posture. The present study aimed to establish a timeline of lower-limb development using a precise measurement of femoral posture. Magnetic resonance images of 157 human embryonic samples (Carnegie stages [CS] 19–23) and 18 fetal samples (crown rump length: 37.2–225 mm) from the Kyoto Collection were obtained. Three-dimensional coordinates of eight selected landmarks in the lower limbs and pelvis were used to calculate the femoral posture. Hip flexion was approximately 14° at CS19 and gradually increased to approximately 65° at CS23; the flexion angle ranged from 90° to 120° during the fetal period. Hip joint abduction was approximately 78° at CS19 and gradually decreased to approximately 27° at CS23; the average angle was approximately 13° during the fetal period. Lateral rotation was greater than 90° at CS19 and CS21 and decreased to approximately 65° at CS23; the average angle was approximately 43° during the fetal period. During the embryonic period, three posture parameters (namely, flexion, abduction, and lateral rotation of the hip) were linearly correlated with each other, suggesting that the femoral posture at each stage was three-dimensionally constant and exhibited gradual and smooth change according to growth. During the fetal period, these parameters varied among individuals, with no obvious trend. Our study has merits in that lengths and angles were measured on anatomical landmarks of the skeletal system. Our obtained data may contribute to understanding development from anatomical aspects and provide valuable insights for clinical application.

松成さんの卒業研究がAnat Recに掲載

中脳が大脳に覆われていない時期の硬膜

松成さんの卒業研究がAnat Recに掲載されました。

硬膜のような袋状の構造物は、組織形態学的手法では立体的な形状がとらえにくかったのですが、MRI等の立体情報の活用により可能になりました。

  • 胚子期から胎児期の64個体の小脳テントの形成について、脳の形態との相互関係から立体的に解析
  • 小脳テントの特徴により、胚子期、胎児期初期、中期にわけられる
  • 大脳の後方への成長、中脳屈曲の解消等の脳形成時の変化がテントの形状や位置に影響をあたえる

59. Matsunari C, Kanahashi T, Otani H, Imai H, Yamada S, Okada T, Takakuwa T. Tentorium cerebelli formation during human embryonic and early fetal development. Anat Rec (Hoboken) 2023, 306(3), 515-526

Abstract

The morphologies of the fetal tentorium cerebelli (TC) and brain influence each other during development. This study aimed to analyze and more comprehensively understand the three-dimensional morphogenesis of the TC and fetal brain. We examined magnetic resonance imaging from 64 embryonic and fetal specimens (crown-rump length range, 9.2–225 mm). During the embryonic period, the lateral folds of the TC elongated to traverse the middle part of the midbrain. The TC and falx cerebri appeared separated, and no invaginations at the parieto-occipital region were observed. In the early fetal period, the cerebrum covered approximately half of the midbrain. The separation of the dural limiting layer at the parieto-occipital region widened from the posterior cerebrum to the cranial cerebellum. The lateral folds of the TC were spread between its tip, continuous with the falx cerebri, and its base plane, located between the midbrain and rostral hindbrain. Differences in the TC components’ growth directions gradually diminished as the cerebrum covered the midbrain. We observed rotation of the TC at its median section according to its growth, which ceased in the middle fetal period. The brainstem and cerebellum extended inferiorly via differential growth, with the cerebrum covering them superiorly. The morphology of the TC curved to conform to the cerebellar and cerebral surfaces. Our present study suggests that factors affecting TC morphology differ between the early and middle fetal periods. Present data provided a more comprehensive view of TC formation according to developmental stage.