There are three major salivary glands located bilaterally outside the oral cavity with long ducts that convey the saliva to the mouth. https://link.springer.com/chapter/10.1007/978-3-031-38567-4_6
Interface Oral Health Science 2009 Conference paper Cleft formation and branching morphogenesis of salivary gland: exploration of new functional genes https://link.springer.com/chapter/10.1007/978-4-431-99644-6_2
FGF signaling regulates salivary gland branching morphogenesis by modulating cell adhesion Ayan T. Ray, Philippe Soriano 20 March 2023 DEVELOPMENT https://journals.biologists.com/dev/article/150/6/dev201293/297264/FGF-signaling-regulates-salivary-gland-branching
Salivary Gland Branching Morphogenesis — Recent Progress and Future Opportunities Int J Oral Sci, 2(3): 117–126, 2010 https://www.nature.com/articles/ijos201017.pdf
Epithelial branching morphogenesis of salivary gland: exploration of new functional regulators Takaoshi Sakai The Journal of Medical Investigation 56 suppl. 2009.https://www.jstage.jst.go.jp/article/jmi/56/Supplement/56_Supplement_234/_pdf
こういった管が分岐するメカニズムにはどれくらい共通性があるのでしょうか。
分岐について比較検討した論文
Patterned cell and matrix dynamics in branching morphogenesis Rockefeller University Press Journal of Cell Biology (JCB) February 2017216(3):jcb.201610048 DOI:10.1083/jcb.201610048 LicenseCC BY-NC-SA 4.0https://www.researchgate.net/publication/313466383_Patterned_cell_and_matrix_dynamics_in_branching_morphogenesis
唾液腺の分岐メカニズムに関する理論的な考察をした論文
Inflationary theory of branching morphogenesis in the mouse salivary gland Ignacio Bordeu, Lemonia Chatzeli & Benjamin D. Simons Nature Communications volume 14, Article number: 3422 (2023) Published: 09 June 2023 https://www.nature.com/articles/s41467-023-39124-x we propose that the gland develops as a tip-driven branching-delayed random walk (BDRW).
Introduction – Lung Development by John McLachlan, PhD Lecturio.com
Histological Differentiation – Lung Development by John McLachlan, PhD Lecturio.com LECTURIOの講義動画ではいろいろな教科書から挿絵が借用されていますが、この動画ではカールソン Carlsonの教科書の図が多用されていました。なので、Carlsonの教科書を読みながらこの動画を視聴したり、逆にこの動画を見たあとでカールソンの教科書を読み直したりすると効果的に勉強できます。
Transverse View – Lung Development by John McLachlan, PhD Lecturio.com 胎児は生まれるまえに「呼吸」をしており羊水を肺に吸い込んでいるそうです。しかし生まれてきて最初の呼吸をしたあとは、肺の中に残っている液体は肺胞で毛細血管に吸収されて、問題は生じないようです。
Respiratory Distress Syndrome – Lung Development by John McLachlan, PhD Lecturio.com
Tracheo-esophageal Fistulas – Lung Development by John McLachlan, PhD Lecturio.com
腸管から気管が分化するときのシグナル
肺は消化管から芽を出すことで作られます。
Fig. 1. Overview of the stages of lung development. Lung endoderm specification begins at ∼E9.0 on the ventral side of the anterior foregut endoderm (yellow) where initiation of Nkx2.1 expression commences. https://europepmc.org/article/pmc/pmc3899811
気管の分岐の分子シグナル
Specification and early development of the lung endoderm. (A) The lung endoderm (marked by Nkx2.1 expression, blue) is first specified on the ventral side of the anterior foregut at E9.0. Wnt2/2b and Bmp4 signaling (indicated in orange???) from the surrounding mesoderm is required for this specification and for patterning of the anterior foregut in a ventral-dorsal manner. Wnt2 and Wnt2b signal via β-catenin to promote the expression of Nkx2.1 whereas Bmp4 represses the inhibitory action of Sox2 on Nkx2.1 expression. (B) During lung development, Fgf10 is essential for branching morphogenesis and is expressed in the mesenchyme surrounding developing branch points (Fgf10 expression indicated in green). This expression is restricted by epithelial expression of genes such Shh and Bmp4 (purple). Fgf10 also directs the orientation of epithelial cell division through regulation of Ras/Sprouty, setting up the appropriate direction of branch growth. https://europepmc.org/article/pmc/pmc3899811
FGF-Regulated ETV Transcription Factors Control FGF-SHH Feedback Loop in Lung Branching Developmental Cell Volume 35, Issue 3, 9 November 2015, Pages 322-332 Journal home page for Developmental Cell Article https://www.sciencedirect.com/science/article/pii/S153458071500653X
Figure 1. Epithelial-mesenchymal cross-talk and governing signalling during early development and branching morphogenesis of lung. Factors are represented only at sites where the expression is most abundant. Fibroblast growth factor-10 (FGF-10) is highly expressed in the distal mesenchyme and acts as a chemotactic focus for the epithelium during lung budding. FGF-10 also regulates Sox9 expression in the distal epithelial progenitors and induces bone morphogenetic protein (BMP)-4 expression. Sox2 expression in the proximal epithelium is under regulation of histone deacetylases 1/2 (HDAC1/2) signalling. FGF-10 expression in the mesenchyme is regulated by Wnt/β-catenin signalling (red arrow). A high concentration of BMP-4 signal also serves to locally inhibit endoderm proliferation, thereby inducing the lateral outgrowth of new airway branches. Sonic hedgehog (Shh) at the distal tips functions to downregulate FGF-10 expression in the mesenchyme, which limits local budding. Transforming growth factor-β (TGF-β) signalling also prevents local budding, by decreasing endodermal proliferation and by stimulating synthesis of matrix components at branch points. Solid arrows indicate sources from and influences on cells/molecules; dotted arrow indicates direction of patterning.
https://www.mdpi.com/1422-0067/17/1/128
FIGURE 1. A Wnt7b-Fgf10 epithelial-mesenchymal crosstalk maintains distal epithelial progenitors during lung development and becomes reactivated in the adult lung to regenerate injured airway epithelium. (A) During the branching stage of lung development, Fgf10 is expressed by mesenchymal progenitor cells, which depends on Wnt/β-catenin signaling, and acts on the distal epithelium to induce Bmp4 and Sox9 expression to keep them in an undifferentiated state. As the epithelial tube grows toward the Fgf10 source, Sox9 + progenitors acquire more proximal positions, switch on Sox2 expression and acquire bronchial epithelial fate. Simultaneously, distal Fgf10-expressing airway smooth muscle (ASMC) progenitors encounter epithelial Bmp4 and Shh (not shown) causing them to stop expressing Fgf10 and differentiate into mature ASMCs as they relocate proximally.
Fgf10 Signaling in Lung Development, Homeostasis, Disease, and Repair After Injury MINI REVIEW article Front. Genet., 25 September 2018 Sec. Stem Cell Research Volume 9 – 2018 | https://doi.org/10.3389/fgene.2018.00418 https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2018.00418/full
AT1 cells cover 95% of the gas exchange surface and are 0.1 µm thick to allow passive diffusion of oxygen into the blood stream. https://www.pnas.org/doi/full/10.1073/pnas.1906663116
The greater omentum is a four-layered peritoneal membrane that extends from the greater curvature of the stomach and covers the entire intestines like an apron. Two layers emerge from the stomach’s front and back, and two layers emerge from the transverse colon’s front and back.