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: 3 complete abstracts (548 words), 9 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
Collections of differentiated cells, such as epithelium; connective tissue; muscles; and nerve tissue. Tissues are cooperatively arranged to form organs with specialized functions such as respiration; digestion; reproduction; movement; and others.
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: Tissue.
Where it fits in the MeSH classification
- Broader topics
- Anatomy Category
- Narrower topics
- Body Fluid Compartments; Connective Tissue; Epithelium; Exocrine Glands; Lymphoid Tissue; Margins of Excision; Membranes; Muscles; Nerve Tissue; Organoids; Parenchymal Tissue; Peritoneal Stomata; Surgically-Created Structures
Related concepts
- Cells
- Epithelium
- Connective Tissue
- Muscles
- Nerve Tissue
- Respiration
- Digestion
- Reproduction
- Movement
Research landscape
PubMed indexes 2,154,894 records tagged with the MeSH heading “Tissues” (counts retrieved 2026-10-31). 293,895 of them (13.6%) were published from 2020 onward, and the busiest period so far is through 1999 with 960,341 records.
Reviews account for 195,801 records (9.1%) and meta-analyses for 7,109. Randomized controlled trials number 34,138 (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 | 960,341 |
| 2000-2009 | 411,984 |
| 2010-2019 | 488,674 |
| 2020 onward | 293,895 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 195,801 | 9.1% |
| Meta-analyses | 7,109 | 0.3% |
| Randomized controlled trials | 34,138 | 1.6% |
Method: PubMed query "Tissues"[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 |
|---|---|---|---|---|
| The molecular footprint of valproic acid in human hippocampal organoid | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42897295 · DOI · PMC13680533 |
| High-fat diet-derived metabolite uridine diphosphate (UDP) impairs epithelial regeneration by P2Y 6 -receptor signaling | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42881530 · DOI · PMC13682407 |
| Success of femtosecond laser-assisted deep anterior lamellar keratoplasty (Femto-DALK): a clinical case series of 42 eyes using an intraoperative optical coherence tomography (iOCT)-guided laser-generated pre-descemet tunnel | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42875753 · DOI · PMC13670811 |
The molecular footprint of valproic acid in human hippocampal organoid [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Autism spectrum disorder (ASD) is a multifaceted neurodevelopmental condition characterized by neuroinflammation, and disruption in neuronal development.
- Closing excerpt
- These findings highlight the contribution of miRNA-mediated regulatory mRNA networks to VPA-induced neuroinflammation-associated with ASD in hHOs.
- 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 (145 words)
Autism spectrum disorder (ASD) is a multifaceted neurodevelopmental condition characterized by neuroinflammation, and disruption in neuronal development. Valproic acid (VPA) is a known environmental risk factor for ASD. Induced pluripotent stem cells (IPSCs IMR90-4)-derived human hippocampal organoids (hHOs) at 60 days of development were used to investigate VPA-induced changes in mRNA and microRNA (miRNA) profiles. The molecular effects of VPA on hHOs were deciphered by meaningfully integrating the ability of miRNA to regulate expression of their predicted mRNA targets crucial to altering neuroinflammatory pathways. Molecular footprint can be defined as the VPA-induced changes to the miRNA profile resulting in coordinated post-transcriptional (mRNA) regulation of neuronal and inflammatory pathways associated with ASD. Based on the results, the molecular footprint of VPA in hHOs was generated for the first time. These findings highlight the contribution of miRNA-mediated regulatory mRNA networks to VPA-induced neuroinflammation-associated with ASD in hHOs.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42897295 · DOI · PMC13680533
High-fat diet-derived metabolite uridine diphosphate (UDP) impairs epithelial regeneration by P2Y 6 -receptor signaling [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Obesity is associated with a chronic low-grade inflammation affecting metabolic changes and organ dysfunction.
- Closing excerpt
- These findings link impaired epithelial regeneration to the onset of obesity-associated low-grade inflammation.
- 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 (235 words)
Obesity is associated with a chronic low-grade inflammation affecting metabolic changes and organ dysfunction. Impairment of the intestinal epithelial barrier (IEB) and alterations in gut microbiota are considered to contribute to this phenotype by largely undefined mechanisms. Here, we used a diet-induced obesity model in rats to investigate the early interplay between a high-fat diet (HFD), gut microbiota composition, metabolic stool contents and IEB regeneration. Male Wistar rats received either a high-fat diet or a low-fat diet (LFD) ad libitum. HFD feeding resulted in weight gain and impaired oral glucose tolerance. Impairment of IEB function was evident by augmented lipopolysaccharide levels in the blood and reduced expression of junctional proteins Claudin-3, 4, and Desmoglein-2 in colonic samples of HFD rats. 16S-rRNA marker-gene sequencing of colonic microbiota revealed decreased phylogenetic diversity in HFD rats and significant alterations in microbial community composition. Detailed analysis revealed that content from HFD rats impaired intestinal epithelial regeneration in organoid assays. Metabolomic profiling identified uridine monophosphate/uridine diphosphate (UMP/UDP) metabolites as strongly enriched in HFD samples. UDP emerged as a key metabolite mediating impaired epithelial regeneration through P2Y6 receptor signaling, as pharmacological inhibition of P2Y6 with antagonist MRS2578 attenuated both UDP- and HFD-induced loss of epithelial regeneration. In summary, these data demonstrate that the diet-dependent stool metabolite UDP compromises intestinal epithelial repair via P2Y6 receptor signaling in early obesity. These findings link impaired epithelial regeneration to the onset of obesity-associated low-grade inflammation.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42881530 · DOI · PMC13682407
Success of femtosecond laser-assisted deep anterior lamellar keratoplasty (Femto-DALK): a clinical case series of 42 eyes using an intraoperative optical coherence tomography (iOCT)-guided laser-generated pre-descemet tunnel [3]
Abstract reading summary — source excerpts
- Opening excerpt
- PurposeTo evaluate the success of Femto-DALK with an iOCT-guided generated intrastromal pre-Descemet tunnel.
- Closing excerpt
- ConclusionFemto-DALK with an iOCT-guided pre-Descemet tunnel generation is a feasible technique that achieves BB success rates comparable to the upper range reported for manual dissection, without a clear demonstrated improvement over manual technique.
- 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 (168 words)
PurposeTo evaluate the success of Femto-DALK with an iOCT-guided generated intrastromal pre-Descemet tunnel.MethodsThis monocentric, retrospective study evaluated all patients treated with Femto-DALK between January 2020 and December 2023 at the Department of Ophthalmology at the University of Düsseldorf (Germany). The iOCT-guided tunnel was generated 30 microns anterior of Descemet's membrane. BB generation, surgery time and conversion to penetrating keratoplasty (PK) were analyzed.ResultsA total of 42 eyes of 41 patients were identified. BB creation was successful in 78.6% of cases. Intraoperative conversion to PK was necessary in 28.6% of the eyes and microperforation of Descemet's membrane (DM) occurred in 16.7% of completed DALKs. Mean operation time was 118.6 ± 40.68 min. Among successful Femto-DALKs (n = 30), double anterior chamber was observed in 26.7%, and re-bubbling was needed in 23.3%. Re-keratoplasty was performed in one eye (3.3%).ConclusionFemto-DALK with an iOCT-guided pre-Descemet tunnel generation is a feasible technique that achieves BB success rates comparable to the upper range reported for manual dissection, without a clear demonstrated improvement over manual technique.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42875753 · DOI · PMC13670811
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 Sex differences in human skeletal muscle fiber types and the influence of age, physical activity, and muscle group: A systematic review and meta-analysis [4]
- Research article Quadriceps, hamstring and patella tendon autografts for primary anterior cruciate ligament reconstruction demonstrate similar clinical outcomes, including graft failure, joint laxity and complications: A systematic review with meta-analysis of randomised controlled trials [5]
- Research article The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains [6]
- Research article Pretreatment Skeletal Muscle Index and Survival Outcomes in Non-Metastatic Colorectal Cancer: A Systematic Review and Meta-Analysis [7]
- Research article The effects of eccentric versus traditional resistance training on muscle strength, power, hypertrophy, and functional performance in older adults: A systematic review with multilevel meta-analysis of randomized controlled trials [8]
- Research article Mechanical isolation of stromal vascular fraction from adipose tissue: methods and cellular outcomes: a systematic review and meta-analysis [9]
References
- Pokharel BR, Cook PP, Akula SM. The molecular footprint of valproic acid in human hippocampal organoid. . 2026. PMID 42897295 · DOI · PMC13680533
- Springer R, Claus P, Hörner M, Otto C, Burkard N, Lauerer J, et al.. High-fat diet-derived metabolite uridine diphosphate (UDP) impairs epithelial regeneration by P2Y 6 -receptor signaling. . 2026. PMID 42881530 · DOI · PMC13682407
- Otto NR, Steindor FA, Geerling G, Seiler TG. Success of femtosecond laser-assisted deep anterior lamellar keratoplasty (Femto-DALK): a clinical case series of 42 eyes using an intraoperative optical coherence tomography (iOCT)-guided laser-generated pre-descemet tunnel. . 2026. PMID 42875753 · DOI · PMC13670811
- James JJ, Mellow ML, Bueckers EP, Gutsch SB, Wrucke DJ, Pearson AG, et al.. Sex differences in human skeletal muscle fiber types and the influence of age, physical activity, and muscle group: A systematic review and meta-analysis. Physiol Rep. 2025. PMID 41178056 · DOI · PMC12580412
- White T, Castro M, Antonio L, Hing W, Tudor F, Sattler L. Quadriceps, hamstring and patella tendon autografts for primary anterior cruciate ligament reconstruction demonstrate similar clinical outcomes, including graft failure, joint laxity and complications: A systematic review with meta-analysis of randomised controlled trials. Knee Surg Sports Traumatol Arthrosc. 2026. PMID 40679231 · DOI · PMC13122740
- Pelland JC, Remmert JF, Robinson ZP, Hinson SR, Zourdos MC. The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains. Sports Med. 2026. PMID 41343037 · DOI
- Atuiri C, Ngang IC, Appiah D, Batchi-Bouyou AL, Matthew KA, Girma AZ, et al.. Pretreatment Skeletal Muscle Index and Survival Outcomes in Non-Metastatic Colorectal Cancer: A Systematic Review and Meta-Analysis. J Gastrointest Cancer. 2025. PMID 40576903 · DOI
- Chaabene H, Müller P, Dhahbi W, Königstein K, Taubert M, Markov A, et al.. The effects of eccentric versus traditional resistance training on muscle strength, power, hypertrophy, and functional performance in older adults: A systematic review with multilevel meta-analysis of randomized controlled trials. Ageing Res Rev. 2026. PMID 41192799 · DOI
- Sforza M, Ivanenko O, Biabani N, Sforza L, Kalaskar DM, Mohri Z, et al.. Mechanical isolation of stromal vascular fraction from adipose tissue: methods and cellular outcomes: a systematic review and meta-analysis. Stem Cell Res Ther. 2025. PMID 41088425 · DOI · PMC12522944
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.