Three‐dimensional analysis of the segmental arrangement of lower lung lobes in human fetuses: is this arrangement a miniature version of adult morphology?. Issue 6 (5th February 2020)

• Record Type: Journal Article
• Authors: Cai, Peiyun; You, Yaqian; Jin, Zhe‐Wu; Murakami, Gen; Wilting, Jőrg; Hayashi, Shogo; Rodríguez‐Vázquez, Jose Francisco
• Is Part Of: Journal of anatomy. Volume 236:Issue 6(2020)
• Page Start: 1021
• Page End: 1034
• Publication Date: 2020-02-05
• Subjects: human embryo and fetus -- individual variations -- lung lower segment -- subsegmental bronchi -- topographical anatomy; Anatomy -- Periodicals; 571.3
• DOI: 10.1111/joa.13157
• Languages: English
• ISSNs: 0021-8782

Abstract

Abstract: Knowledge of the lung segment system is essential for understanding human anatomy and has great clinical relevance. The arrangement of 11 segments, including the S* or subsuperior segment, and its individual variations, are considered to be the same in fetal and adult lungs. The present study assessed the topographical anatomy of lower segmental and subsegmental bronchi by computer‐assisted three‐dimensional imaging of serial sagittal sections of both lungs of 22 embryos and fetuses of gestational age 6–7 weeks (crown–rump length 15.0–28.5 mm). Long inferior courses of B8b (basal) and B10c (medial) were observed in sagittal sections of both lungs. B8a (lateral) and B10b (lateral) in the right lungs were consistently underdeveloped, with S9 occupying most of the lateral half of the lower lobe. In some samples, B6b (lateral) did not reach the lateral surface. The lateral dominance of S9 was also seen in the left lungs. Some B* candidates were present, but B7 candidates were absent. Lateral and posterior expansions of S6b, S8a and S10b to cover S9 were observed in additional midterm and near‐term lung sections, indicating that the original S9 dominance was 'corrected' by an increase in lung volume. Delayed growth of the lower lateral subsegments might induce mechanical stress, resulting in aberrant notches or fissures, such as those separating an independent posterior lobe. The segmental arrangement of fetal lungs was not stable, but was altered over a long fetal period after the complete subsegmental division of the bronchi, except for the minor bronchi B* and B7. Abstract : Percentage of the variation in arrangement of lung segments in 22 embryos and fetuses at gestational age 6–7 weeks. The five panels on the left‐hand side show the right lower lobes, while the four panels on the right‐hand side show the left lower lobes. Candidates for S*, if present, are regarded as part of S8, S9 or S10, depending on the origin of B*. S9 was found to always occupy the most lateral parts of the right lower lobe. The segmental arrangement of the left lower lobe in these embryos was similar to that in adults.