External ears, one of the major face components, show an interesting movement during craniofacial morphogenesis in human embryo. The present study was performed to see if movement of the external ears in a human embryo could be explained by differential growth. In all, 171 samples between Carnegie stage (CS) 17 and CS 23 were selected from MR image datasets of human embryos obtained from the Kyoto Collection of Human Embryos. The three-dimensional absolute position of 13 representative anatomical landmarks, including external and internal ears, from MRI data was traced to evaluate the movement between the different stages with identical magnification. Two different sets of reference axes were selected for evaluation and comparison of the movements. When the pituitary gland and the first cervical vertebra were selected as a reference axis, the 13 anatomical landmarks of the face spread out within the same region as the embryo enlarged and changed shape. The external ear did move mainly laterally, but not cranially. The distance between the external and internal ear stayed approximately constant. Three-dimensionally, the external ear located in the caudal ventral parts of the internal ear in CS 17, moved mainly laterally until CS 23. When surface landmarks eyes and mouth were selected as a reference axis, external ears moved from the caudal lateral ventral region to the position between eyes and mouth during development. The results indicate that movement of all anatomical landmarks, including external and internal ears, can be explained by differential growth. Also, when the external ear is recognized as one of the facial landmarks and having a relative position to other landmarks such as the eyes and mouth, the external ears seem to move cranially.
1. Hirose A, Nakashima T, Yamada S, Uwabe C, Kose K, Takakuwa T, Embryonic liver morphology and morphometry by magnetic resonance microscopic imaging , Anat Rec (Hoboken). 2012 Jan;295(1):51-9., doi; 10.1002/ar.21496
Abstract
Embryonic liver has a unique external morphology and quantitative morphometry, based on magnetic resonance imaging data of human embryos from the Kyoto Collection of Human Embryos. Liver morphogenesis is strongly affected by the adjacent organs and tissues. The left ventricle develops to the left medial-caudal side, which results in the formation of a depression at left medial region and a prominence bilaterally at the cranial surface of the liver between Carnegie Stage (CS)17 and CS19. An imprint of the stomach that formed at the dorsal left-medial region of the liver became more marked with development until CS23. A depression induced by the umbilicus formed at the ventral region of the liver between CS16 and CS19. An indentation caused by the right adrenal gland formed at the dorsal-caudal region of the liver surface from CS20. Morphometric analysis revealed that the volume of the liver increased exponentially from CS14 through CS23. The liver developed preferentially along the dorsoventral axis and right/left axis until CS17, along the craniocaudal axis between CS17 and CS19, and then in all directions after CS19. Several important developmental phenomena, such as differentiation of the diaphragm, the extension of the body axis of the embryo, and the physiologic herniation of the intestine into the umbilical cord, may affect morphometric data. These data contribute to a better understanding of liver development as well as the morphogenesis of adjacent organs, both temporally and spatially, and serve as a useful reference for fetal medicine and prenatal diagnosis.
2. Nakashima T, Hirose A, Yamada S, Uwabe C, Kose K, Takakuwa T, Morphometric analysis of the brain vesicles during the human embryonic period by magnetic resonance microscopic imaging, Congenit Anom (Kyoto). 2012 Mar;52(1):55-8, doi; 10.1111/j.1741-4520.2011.00345.x （概要), [OpenAccess]
次世代の医療は、医学研究科だけでなく、さまざまな分野の学生が担って行く可能性があります。今回は、その代表として理工学、細胞生物学、地域・社会学からのアプローチを取り上げ、医療の動向を議論したいと思います。本プログラムを聴講した様々な分野の学生が、次世代の医療に繋がるヒントを得て、思いもかけない連携が生まれるかもしれません。それは、この上なく喜ばしいことです。
