Left/right difference in the course and division of the pulmonary arterial branches in the lung upper lobe: A study using human embryos and early fetuses

Abstract

Although left/right differences in a configuration of the pulmonary artery (PA) and its branches are well known, there is little information as to when and how such differences are established. Examination of serial sagittal sections of 25 embryos and fetuses at 6-7 weeks of gestation demonstrated that, at O'Rahilly stages 18-20, How to cite this article: Jin ZW, Hayashi S, Murakami G, Wilting J, Rodríguez-Vázquez JF, Abe S. Left/right difference in the course and division of the pulmonary arterial branches in the lung upper lobe: A study using human embryos and early fetuses.

Lung fusion with the liver in chick and quail embryos

“…However, the tight attachment was seen also in human embryos at 5 weeks. Likewise, at 6 weeks, only a narrow coelomic cavity separates the lung from the liver in human embryos because the diaphragm is still underdeveloped (Cai et al, 2020; Jin et al, 2020). Did the well‐differentiated mesothelial coverings interfere with the lung–liver fusion or attachment of their mesenchymal cells in humans?…”

“…However, the tight attachment was seen also in human embryos at 5 weeks. Likewise, at 6 weeks, only a narrow coelomic cavity separates the lung from the liver in human embryos because the diaphragm is still underdeveloped (Cai et al, 2020;Jin et al, 2020).…”

“…

The diaphragm separates the lung and liver in adult mammals.However, in human embryos before development of the muscular diaphragm, the lung faces the liver with a separation by the thin pleura and narrow pleural cavity: thus, a mesothelium-to-mesothelium attachment is likely (Cai et al, 2020;Hayashi et al, 2011;Jin et al, 2020). In adult birds, instead of the muscular diaphragm, the costopleuralis muscle (striated muscle; analogy of the subcostalis in mammals) separates the posteriorly restricted lung from the liver (DeWet et al, 1967).

…”