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Updated: Jan 20, 2026

Culture and Maintenance of Human Embryonic Stem Cells
Published on: December 22, 2009
Human embryonic ribs all progress through common morphological forms irrespective of their position on the axis
Jun Matsubayashi1, Kasumi Okuno1, Sena Fujii1
1Human Health Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
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.
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