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 (627 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 thick, yellowish-white, viscid fluid secretion of male reproductive organs discharged upon ejaculation. In addition to reproductive organ secretions, it contains spermatozoa and their nutrient plasma.
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: Seminal Plasma; Plasma, Seminal.
Where it fits in the MeSH classification
- Broader topics
- Bodily Secretions
- See also
- Sperm Banks; Spermatozoa
Related concepts
Research landscape
PubMed indexes 26,983 records tagged with the MeSH heading “Semen” (counts retrieved 2026-10-31). 7,548 of them (28.0%) were published from 2020 onward, and the busiest period so far is through 1999 with 10,820 records.
Reviews account for 2,219 records (8.2%) and meta-analyses for 189. Randomized controlled trials number 385 (1.4%) 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 | 10,820 |
| 2000-2009 | 3,976 |
| 2010-2019 | 4,639 |
| 2020 onward | 7,548 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 2,219 | 8.2% |
| Meta-analyses | 189 | 0.7% |
| Randomized controlled trials | 385 | 1.4% |
Method: PubMed query "Semen"[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 |
|---|---|---|---|---|
| Human fertilization in vivo and in vitro requires the CatSper channel to initiate sperm hyperactivation | 2024 | Research article Design not recorded in structured metadata | 41 | cc by PMID 38165034 · DOI · PMC10760960 |
| Derivation of human primordial germ cell-like cells in an embryonic-like culture | 2024 | Research article Design not recorded in structured metadata | 37 | cc by PMID 38167821 · DOI · PMC10762101 |
| RNA polymerase II pausing is essential during spermatogenesis for appropriate gene expression and completion of meiosis | 2024 | Research article Design not recorded in structured metadata | 32 | cc by PMID 38287033 · DOI · PMC10824759 |
| Novel HPLC-laser-stimulated fluorescence profiling of seminal plasma amino acids linked to ejaculate quality | 2026 | Research article Design not recorded in structured metadata | 0 | cc by PMID 42390790 · DOI · PMC13598000 |
Human fertilization in vivo and in vitro requires the CatSper channel to initiate sperm hyperactivation [1]
Abstract reading summary — source excerpts
- Opening excerpt
- The infertility of many couples rests on an enigmatic dysfunction of the man's sperm.
- Closing excerpt
- Finally, our study also revealed that defective CatSper function and ensuing failure to hyperactivate represents the most common cause of unexplained male infertility known thus far and that this sperm channelopathy can readily be diagnosed, enabling future evidence-based treatment of affected couples.
- 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 (199 words)
The infertility of many couples rests on an enigmatic dysfunction of the man's sperm. To gain insight into the underlying pathomechanisms, we assessed the function of the sperm-specific multisubunit CatSper-channel complex in the sperm of almost 2,300 men undergoing a fertility workup, using a simple motility-based test. We identified a group of men with normal semen parameters but defective CatSper function. These men or couples failed to conceive naturally and upon medically assisted reproduction via intrauterine insemination and in vitro fertilization. Intracytoplasmic sperm injection (ICSI) was, ultimately, required to conceive a child. We revealed that the defective CatSper function was caused by variations in CATSPER genes. Moreover, we unveiled that CatSper-deficient human sperm were unable to undergo hyperactive motility and, therefore, failed to penetrate the egg coat. Thus, our study provides the experimental evidence that sperm hyperactivation is required for human fertilization, explaining the infertility of CatSper-deficient men and the need of ICSI for medically assisted reproduction. Finally, our study also revealed that defective CatSper function and ensuing failure to hyperactivate represents the most common cause of unexplained male infertility known thus far and that this sperm channelopathy can readily be diagnosed, enabling future evidence-based treatment of affected couples.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 38165034 · DOI · PMC10760960
Derivation of human primordial germ cell-like cells in an embryonic-like culture [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Primordial germ cells (PGCs) are the embryonic precursors of sperm and eggs.
- Closing excerpt
- hPGCLCs are successfully derived from eight non-obstructive azoospermia (NOA) participant-derived hPSC lines using this biomimetic platform, demonstrating its promise for screening applications.
- 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 (137 words)
Primordial germ cells (PGCs) are the embryonic precursors of sperm and eggs. They transmit genetic and epigenetic information across generations. Given the prominent role of germline defects in diseases such as infertility, detailed understanding of human PGC (hPGC) development has important implications in reproductive medicine and studying human evolution. Yet, hPGC specification remains an elusive process. Here, we report the induction of hPGC-like cells (hPGCLCs) in a bioengineered human pluripotent stem cell (hPSC) culture that mimics peri-implantation human development. In this culture, amniotic ectoderm-like cells (AMLCs), derived from hPSCs, induce hPGCLC specification from hPSCs through paracrine signaling downstream of ISL1. Our data further show functional roles of NODAL, WNT, and BMP signaling in hPGCLC induction. hPGCLCs are successfully derived from eight non-obstructive azoospermia (NOA) participant-derived hPSC lines using this biomimetic platform, demonstrating its promise for screening applications.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 38167821 · DOI · PMC10762101
RNA polymerase II pausing is essential during spermatogenesis for appropriate gene expression and completion of meiosis [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Male germ cell development requires precise regulation of gene activity in a cell-type and stage-specific manner, with perturbations in gene expression during spermatogenesis associated with infertility.
- Closing excerpt
- Further, we uncover unanticipated roles for Pol II pausing in the regulation of meiosis during spermatogenesis, with the presence of paused Pol II associated with double-strand break (DSB) formation, and disruption of meiotic gene expression and DSB repair in germ cells lacking NELF.
- 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 (148 words)
Male germ cell development requires precise regulation of gene activity in a cell-type and stage-specific manner, with perturbations in gene expression during spermatogenesis associated with infertility. Here, we use steady-state, nascent and single-cell RNA sequencing strategies to comprehensively characterize gene expression across male germ cell populations, to dissect the mechanisms of gene control and provide new insights towards therapy. We discover a requirement for pausing of RNA Polymerase II (Pol II) at the earliest stages of sperm differentiation to establish the landscape of gene activity across development. Accordingly, genetic knockout of the Pol II pause-inducing factor NELF in immature germ cells blocks differentiation to spermatids. Further, we uncover unanticipated roles for Pol II pausing in the regulation of meiosis during spermatogenesis, with the presence of paused Pol II associated with double-strand break (DSB) formation, and disruption of meiotic gene expression and DSB repair in germ cells lacking NELF.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 38287033 · DOI · PMC10824759
Novel HPLC-laser-stimulated fluorescence profiling of seminal plasma amino acids linked to ejaculate quality [4]
Abstract reading summary — source excerpts
- Opening excerpt
- PurposeAmino acids are vital biomolecules that can provide important insights into sperm functional competence.
- Closing excerpt
- The low relative abundance of AA in the non-normozoospermic men could be attributed to aberrant metabolic pathways, underscoring their significance in male infertility.
- 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 (143 words)
PurposeAmino acids are vital biomolecules that can provide important insights into sperm functional competence. However, the level of amino acids (AAs) in seminal plasma and their implications on sperm characteristics remain less understood.MethodsFor the first time, high-performance liquid chromatography (HPLC) in combination with a laser-stimulated fluorescence (LSF) system was used to profile AAs from the seminal plasma of 30 normozoospermic and 51 nonnormozoospermic ejaculates. Sperm characteristics, along with DNA integrity, were assessed and correlated with individual AAs.ResultsThe HPLC-LSF system was able to detect a total of 18 AAs in the seminal plasma. A significant variation was observed between the two groups for all AAs (p ConclusionThe HPLC-LSF platform could serve as a potential tool in identifying seminal plasma AA levels. The low relative abundance of AA in the non-normozoospermic men could be attributed to aberrant metabolic pathways, underscoring their significance in male infertility.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42390790 · DOI · PMC13598000
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 Temporal trends in sperm count: a systematic review and meta-regression analysis of samples collected globally in the 20th and 21st centuries [5]
- Research article Association between socio-psycho-behavioral factors and male semen quality: systematic review and meta-analyses [6]
- Research article The Female Response to Seminal Fluid [7]
- Research article The Role of Kisspeptin in the Control of the Hypothalamic-Pituitary-Gonadal Axis and Reproduction [8]
- Research article The enigmatic seminal plasma: a proteomics insight from ejaculation to fertilization [9]
- Research article Sexual conflict and seminal fluid proteins: a dynamic landscape of sexual interactions [10]
References
- Young S, Schiffer C, Wagner A, Patz J, Potapenko A, Herrmann L, et al.. Human fertilization in vivo and in vitro requires the CatSper channel to initiate sperm hyperactivation. . 2024. PMID 38165034 · DOI · PMC10760960
- Esfahani SN, Zheng Y, Arabpour A, Irizarry AMR, Kobayashi N, Xue X, et al.. Derivation of human primordial germ cell-like cells in an embryonic-like culture. . 2024. PMID 38167821 · DOI · PMC10762101
- Kaye EG, Basavaraju K, Nelson GM, Zomer HD, Roy D, Joseph II, et al.. RNA polymerase II pausing is essential during spermatogenesis for appropriate gene expression and completion of meiosis. . 2024. PMID 38287033 · DOI · PMC10824759
- Naik M, Meitei HY, Uppangala S, Predheepan D, Adiga SK, Patil A. Novel HPLC-laser-stimulated fluorescence profiling of seminal plasma amino acids linked to ejaculate quality. . 2026. PMID 42390790 · DOI · PMC13598000
- Levine H, Jørgensen N, Martino-Andrade A, Mendiola J, Weksler-Derri D, Jolles M, et al.. Temporal trends in sperm count: a systematic review and meta-regression analysis of samples collected globally in the 20th and 21st centuries. Hum Reprod Update. 2023. PMID 36377604 · DOI
- Li Y, Lin H, Li Y, Cao J. Association between socio-psycho-behavioral factors and male semen quality: systematic review and meta-analyses. Fertil Steril. 2011. PMID 20674912 · DOI
- Schjenken JE, Robertson SA. The Female Response to Seminal Fluid. Physiol Rev. 2020. PMID 31999507 · DOI
- Xie Q, Kang Y, Zhang C, Xie Y, Wang C, Liu J, et al.. The Role of Kisspeptin in the Control of the Hypothalamic-Pituitary-Gonadal Axis and Reproduction. Front Endocrinol (Lausanne). 2022. PMID 35837314 · DOI · PMC9273750
- Samanta L, Parida R, Dias TR, Agarwal A. The enigmatic seminal plasma: a proteomics insight from ejaculation to fertilization. Reprod Biol Endocrinol. 2018. PMID 29704899 · DOI · PMC5923003
- Sirot LK, Wong A, Chapman T, Wolfner MF. Sexual conflict and seminal fluid proteins: a dynamic landscape of sexual interactions. Cold Spring Harb Perspect Biol. 2014. PMID 25502515 · DOI · PMC4315932
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.