Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (1,146 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
The larger air passages of the lungs arising from the terminal bifurcation of the trachea. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into bronchioles and pulmonary alveoli.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Bronchus; Primary Bronchi; Bronchi, Primary; Bronchus, Primary; Primary Bronchus; Secondary Bronchi; Bronchi, Secondary; Bronchus, Secondary.
Where it fits in the MeSH classification
- Broader topics
- Lung
- Narrower topics
- Bronchioles
- See also
- Bronchodilator Agents; Bronchography; Bronchoscopy; Bronchoconstrictor Agents
Related concepts
- Trachea
- Bronchioles
- Pulmonary Alveoli
Research landscape
PubMed indexes 44,230 records tagged with the MeSH heading “Bronchi” (counts retrieved 2026-10-31). 2,968 of them (6.7%) were published from 2020 onward, and the busiest period so far is through 1999 with 27,513 records.
Reviews account for 2,923 records (6.6%) and meta-analyses for 33. Randomized controlled trials number 720 (1.6%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 27,513 |
| 2000-2009 | 6,956 |
| 2010-2019 | 6,793 |
| 2020 onward | 2,968 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 2,923 | 6.6% |
| Meta-analyses | 33 | 0.1% |
| Randomized controlled trials | 720 | 1.6% |
Method: PubMed query "Bronchi"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in anatomy and physiology
Anatomy describes how body structures are built and physiology describes how they normally work, so most findings here are descriptive or mechanistic rather than evidence about treatment. Much of what is known comes from dissection, imaging, tissue studies and experiments in animals, and measurements in healthy volunteers can differ from those in people with disease or at different ages. Normal ranges vary between individuals and populations. Check whether a result was measured in people or in another species, the age and health of the participants, and the method used.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Resveratrol and Pterostilbene Inhibit SARS-CoV-2 Replication in Air-Liquid Interface Cultured Human Primary Bronchial Epithelial Cells | 2021 | Research article Design not recorded in structured metadata | 60 | cc by PMID 34372541 · DOI · PMC8309965 |
| Ferrostatin-1 and 3-Methyladenine Ameliorate Ferroptosis in OVA-Induced Asthma Model and in IL-13-Challenged BEAS-2B Cells | 2022 | Research article Design not recorded in structured metadata | 57 | cc by PMID 35154576 · DOI · PMC8837457 |
| Deep learning for anatomical interpretation of video bronchoscopy images | 2021 | Research article Design not recorded in structured metadata | 33 | cc by PMID 34887497 · DOI · PMC8660867 |
| Epithelial stem cells from human small bronchi offer a potential for therapy of idiopathic pulmonary fibrosis | 2025 | Research article Design not recorded in structured metadata | 14 | cc by PMID 39753035 · DOI · PMC11754162 |
Resveratrol and Pterostilbene Inhibit SARS-CoV-2 Replication in Air-Liquid Interface Cultured Human Primary Bronchial Epithelial Cells [1]
Abstract reading summary — source excerpts
- Opening excerpt
- The current COVID-19 pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has an enormous impact on human health and economy.
- Closing excerpt
- Because these results represent laboratory findings in cells, we advocate evaluation of these compounds in clinical trials before statements are made whether these drugs are advantageous for COVID-19 treatment.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (229 words)
The current COVID-19 pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has an enormous impact on human health and economy. In search for therapeutic options, researchers have proposed resveratrol, a food supplement with known antiviral, anti-inflammatory, and antioxidant properties as an advantageous antiviral therapy for SARS-CoV-2 infection. Here, we provide evidence that both resveratrol and its metabolically more stable structural analog, pterostilbene, exhibit potent antiviral properties against SARS-CoV-2 in vitro. First, we show that resveratrol and pterostilbene antiviral activity in African green monkey kidney cells. Both compounds actively inhibit virus replication within infected cells as reduced virus progeny production was observed when the compound was added at post-inoculation conditions. Without replenishment of the compound, antiviral activity was observed up to roughly five rounds of replication, demonstrating the long-lasting effect of these compounds. Second, as the upper respiratory tract represents the initial site of SARS-CoV-2 replication, we also assessed antiviral activity in air-liquid interface (ALI) cultured human primary bronchial epithelial cells, isolated from healthy volunteers. Resveratrol and pterostilbene showed a strong antiviral effect in these cells up to 48 h post-infection. Collectively, our data indicate that resveratrol and pterostilbene are promising antiviral compounds to inhibit SARS-CoV-2 infection. Because these results represent laboratory findings in cells, we advocate evaluation of these compounds in clinical trials before statements are made whether these drugs are advantageous for COVID-19 treatment.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 34372541 · DOI · PMC8309965
Ferrostatin-1 and 3-Methyladenine Ameliorate Ferroptosis in OVA-Induced Asthma Model and in IL-13-Challenged BEAS-2B Cells [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Ferroptosis was reported to be involved in the occurrence and development of asthma.
- Closing excerpt
- Collectively, Ferr-1 and 3-MA ameliorated asthma in vivo and in vitro through inhibiting ferroptosis, providing a new strategy for the clinical treatment of asthma.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (210 words)
Ferroptosis was reported to be involved in the occurrence and development of asthma. However, the potential mechanism underlying the role of ferroptosis in asthma remains unclear. In this study, we established the mouse asthma model following the ovalbumin (OVA) method in C57BL/6 mice and the cell model with IL-13 induction in bronchial epithelial cells (BEAS-2B cells). Treatment of ferrostatin-1 (Ferr-1) and 3-methyladenine (3-MA) decreased iron deposition in IL-13-induced BEAS-2B cells and lung tissues of asthma mice, opposite to that in bronchoalveolar lavage fluid (BALF). Meanwhile, excessive lipid peroxidation asthma model in vivo and in vitro was alleviated by Ferr-1 or 3-MA treatment. In addition, Ferr-1 and 3-MA inhibited the expression of LC-3 in these cells and lung tissues of mice. Moreover, Ferr-1 and 3-MA also suppressed the production of inflammatory cytokines (IL-1β, IL-6, and TNF-α) and oxidative stress factors (ROS and MDA), while promoting the level of SOD, in vivo and in vitro. Furthermore, application of Ferr-1 exhibited a greater inhibitory effect on iron release and lipid peroxidation in IL-13-induced BEAS-2B cells and asthma mice than 3-MA, accompanied with a weaker effect on ferritinophagy than 3-MA. Collectively, Ferr-1 and 3-MA ameliorated asthma in vivo and in vitro through inhibiting ferroptosis, providing a new strategy for the clinical treatment of asthma.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 35154576 · DOI · PMC8837457
Deep learning for anatomical interpretation of video bronchoscopy images [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Anesthesiologists commonly use video bronchoscopy to facilitate intubation or confirm the location of the endotracheal tube; however, depth and orientation in the bronchial tree can often be confused because anesthesiologists cannot trace the airway from the oropharynx when it is performed using an endotracheal tube.
- Closing excerpt
- This model can be a basis for designing a clinical decision support system with video bronchoscopy.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (386 words)
Anesthesiologists commonly use video bronchoscopy to facilitate intubation or confirm the location of the endotracheal tube; however, depth and orientation in the bronchial tree can often be confused because anesthesiologists cannot trace the airway from the oropharynx when it is performed using an endotracheal tube. Moreover, the decubitus position is often used in certain surgeries. Although it occurs rarely, the misinterpretation of tube location can cause accidental extubation or endobronchial intubation, which can lead to hyperinflation. Thus, video bronchoscopy with a decision supporting system using artificial intelligence would be useful in the anesthesiologic process. In this study, we aimed to develop an artificial intelligence model robust to rotation and covering using video bronchoscopy images. We collected video bronchoscopic images from an institutional database. Collected images were automatically labeled by an optical character recognition engine as the carina and left/right main bronchus. Except 180 images for the evaluation dataset, 80% were randomly allocated to the training dataset. The remaining images were assigned to the validation and test datasets in a 7:3 ratio. Random image rotation and circular cropping were applied. Ten kinds of pretrained models with < 25 million parameters were trained on the training and validation datasets. The model showing the best prediction accuracy for the test dataset was selected as the final model. Six human experts reviewed the evaluation dataset for the inference of anatomical locations to compare its performance with that of the final model. In the experiments, 8688 images were prepared and assigned to the evaluation (180), training (6806), validation (1191), and test (511) datasets. The EfficientNetB1 model showed the highest accuracy (0.86) and was selected as the final model. For the evaluation dataset, the final model showed better performance (accuracy, 0.84) than almost all human experts (0.38, 0.44, 0.51, 0.68, and 0.63), and only the most-experienced pulmonologist showed performance comparable (0.82) with that of the final model. The performance of human experts was generally proportional to their experiences. The performance difference between anesthesiologists and pulmonologists was marked in discrimination of the right main bronchus. Using bronchoscopic images, our model could distinguish anatomical locations among the carina and both main bronchi under random rotation and covering. The performance was comparable with that of the most-experienced human expert. This model can be a basis for designing a clinical decision support system with video bronchoscopy.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 34887497 · DOI · PMC8660867
Epithelial stem cells from human small bronchi offer a potential for therapy of idiopathic pulmonary fibrosis [4]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundIdiopathic pulmonary fibrosis (IPF) is a fibrosing interstitial pneumonia with restrictive ventilation.
- Closing excerpt
- FundingNational Natural Science Foundation of China (82430001, 81930001, and 81900059), Shanghai Shenkang Hospital Development Center (SHDC2020CR3063B), Department of Science and Technology of Shandong Province (2024HWYQ-058).
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (321 words)
BackgroundIdiopathic pulmonary fibrosis (IPF) is a fibrosing interstitial pneumonia with restrictive ventilation. Recently, the structural and functional defects of small airways have received attention in the early pathogenesis of IPF. This study aimed to elucidate the characteristics of small airway epithelial dysfunction in patients with IPF and explore novel therapeutic interventions to impede IPF progression by targeting the dysfunctional small airways.MethodsAirway trees spanning the proximal-distal axis were harvested from control lungs and explanted lungs with end-stage IPF undergoing transplant. Qualified basal cells (BCs, p63/Krt5/ITGA6/NGFR) were expanded, and their cellular functions, feasibility, safety and efficacy for transplantation therapy in IPF were validated with experiments in vitro and mouse model. Single-cell RNA-sequencing was employed to elucidate the underlying mechanisms governing the BCs based therapy. Based upon these evidences, three patients with advanced IPF and small airway dysfunction received autologous-BCs transplantation. Post-transplantation assessments included lung function, exercise capacity and high resolution computed tomography (HRCT) scans were analyzed to quantify the clinical benefits conferred by the BCs transplantation.FindingsAn overall landscape of senescent phenotype in airway epithelial cells and airway stem/progenitor cells along the proximal-distal axis of the airway tree in IPF were outlined. In contrast to the cells situated in distal airways, BCs located in small bronchi in IPF displayed a non-senescent phenotype, with comparable proliferative, differentiative capabilities, and similar transcriptomic profiles to normal controls. In a mouse model of pulmonary fibrosis, BCs exhibited promising protective efficacy and safety for transplantation therapy. Autologous BCs transplantation in three advanced IPF patients with small airway dysfunction yielded significant clinical improvements in pulmonary function, particularly evidence in lung volume and small airway function.InterpretationEpithelia of small bronchi in IPF contain functional and expandable basal stem cells, which exert therapeutic benefits via bronchoscopic implantation. Our findings offer a potential for IPF treatment by targeting small airways.FundingNational Natural Science Foundation of China (82430001, 81930001, and 81900059), Shanghai Shenkang Hospital Development Center (SHDC2020CR3063B), Department of Science and Technology of Shandong Province (2024HWYQ-058).
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 39753035 · DOI · PMC11754162
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Severe and Difficult-to-Treat Asthma in Adults [5]
- Research article Roles of epidermal growth factor receptor activation in epithelial cell repair and mucin production in airway epithelium [6]
- Research article Tissue remodelling in chronic bronchial diseases: from the epithelial to mesenchymal phenotype [7]
- Research article Respiratory syncytial virus (RSV) and its propensity for causing bronchiolitis [8]
- Research article Small airway obstruction in COPD: new insights based on micro-CT imaging and MRI imaging [9]
- Research article Nicotine exposure and bronchial epithelial cell nicotinic acetylcholine receptor expression in the pathogenesis of lung cancer [10]
References
- Ter Ellen BM, Dinesh Kumar N, Bouma EM, Troost B, van de Pol DPI, van der Ende-Metselaar HH, et al.. Resveratrol and Pterostilbene Inhibit SARS-CoV-2 Replication in Air-Liquid Interface Cultured Human Primary Bronchial Epithelial Cells. . 2021. PMID 34372541 · DOI · PMC8309965
- Yang N, Shang Y. Ferrostatin-1 and 3-Methyladenine Ameliorate Ferroptosis in OVA-Induced Asthma Model and in IL-13-Challenged BEAS-2B Cells. . 2022. PMID 35154576 · DOI · PMC8837457
- Yoo JY, Kang SY, Park JS, Cho YJ, Park SY, Yoon HI, et al.. Deep learning for anatomical interpretation of video bronchoscopy images. . 2021. PMID 34887497 · DOI · PMC8660867
- Liu Z, Zheng Q, Li Z, Huang M, Zhong C, Yu R, et al.. Epithelial stem cells from human small bronchi offer a potential for therapy of idiopathic pulmonary fibrosis. . 2025. PMID 39753035 · DOI · PMC11754162
- Israel E, Reddel HK. Severe and Difficult-to-Treat Asthma in Adults. N Engl J Med. 2017. PMID 28877019 · DOI
- Burgel PR, Nadel JA. Roles of epidermal growth factor receptor activation in epithelial cell repair and mucin production in airway epithelium. Thorax. 2004. PMID 15516478 · DOI · PMC1746853
- Pain M, Bermudez O, Lacoste P, Royer PJ, Botturi K, Tissot A, et al.. Tissue remodelling in chronic bronchial diseases: from the epithelial to mesenchymal phenotype. Eur Respir Rev. 2014. PMID 24591669 · DOI · PMC9487272
- Pickles RJ, DeVincenzo JP. Respiratory syncytial virus (RSV) and its propensity for causing bronchiolitis. J Pathol. 2015. PMID 25302625 · DOI · PMC5638117
- Hogg JC, McDonough JE, Suzuki M. Small airway obstruction in COPD: new insights based on micro-CT imaging and MRI imaging. Chest. 2013. PMID 23648907 · DOI · PMC3653349
- Minna JD. Nicotine exposure and bronchial epithelial cell nicotinic acetylcholine receptor expression in the pathogenesis of lung cancer. J Clin Invest. 2003. PMID 12511585 · DOI · PMC151841
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.