1 Department of Reproduction Medical, Sichuan Jinxin Xi’nan Women’s and Children’s Hospital, 610066 Chengdu, Sichuan, China
2 Department of Reproduction Medical, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, 610072 Chengdu, Sichuan, China
Abstract
This review aimed to elucidate the physiological roles of seminal plasma (SP) in modulating female reproductive function, with an emphasis on the mechanisms that optimize the conception microenvironment. Moreover, this review further evaluated the translational potential of SP as an adjunct to assisted reproductive technologies (ARTs).
1. Molecular signaling: SP acted as both a transport medium for spermatozoa and a carrier of male-derived bioactive molecules (e.g., transforming growth factor-β (TGF-β), prostaglandins) that activated Toll-like receptor (TLR)-mediated signaling pathways in female reproductive tissues; 2. Immune modulation: SP triggered a transient inflammatory response in the cervicovaginal mucosa, enhancing pathogen clearance capacity by upregulating neutrophil recruitment and antimicrobial peptide secretion; 3. Receptivity regulation: SP components (particularly extracellular vesicles) modified endometrial epithelial-stromal crosstalk via paracrine interactions, extending the implantation window by modulating Homeobox A10 (HOXA10) expression. 4. Maternal-fetal tolerance: SP-induced regulatory T cell expansion promoted immune acceptance of semi-allogeneic embryos by suppressing Th1/Th17 responses at the decidual interface.
Exposure to SP induced a self-limiting inflammatory cascade that optimized sperm survival and endometrial preparedness in murine and human studies. ART cycles incorporating SP perfusion demonstrated a 14.4% increase in clinical pregnancy rates (pooled odds ratio [OR] = 1.32, 95% confidence interval [CI]: 1.08–1.61) across eight randomized trials. Proteomic analyses identified SP exosomes as critical mediators of endometrial receptivity, though batch variability remained a translational challenge.
SP emerged as a master regulator of peri-conception events through multimodal mechanisms. While preclinical data supported its therapeutic utility in recurrent implantation failure (RIF), standardized protocols for clinical deployment required further validation. Future research should prioritize the mechanistic dissection of exosome-carried microRNAs and large-scale studies of ART outcomes.
Keywords
- seminal plasma
- female reproductive system
- inflammatory response
- immune tolerance
The incidence of infertility is increasing in China. Thus, assisted reproductive technology (ART) represents an effective method for treating infertility. However, the persistently low implantation and clinical pregnancy rates following ART remain a key challenge. This may be due to endometrial-embryo asynchrony caused by controlled ovarian stimulation and the absence of seminal plasma (SP) constituents in non-natural conception. The occurrence of life is not simply the combination of gametes; it involves complex, intricate regulatory mechanisms in both males and females. During reproduction, SP can transport and nourish sperm, thereby enhancing the ability of sperm to fertilize. SP can also regulate maternal–fetal immune tolerance and preimplantation embryo development, affect endometrial receptivity, and promote embryo implantation by stimulating the immune system in the female reproductive tract (FRT) [1, 2]. This article aimed to explore the regulatory effects of male SP on cells across various regions of the FRT and the impact of SP on biological functions. This article also aimed to analyze the regulation of male SP on the physiological functions of the FRT and the influence of SP on ART pregnancy outcomes.
How were the articles selected or found? Our displaying the methods are as follows:
1. Search Strategy
①. Database selection
A tri-database approach was employed to ensure interdisciplinary coverage: PubMed: Focused on biomedical studies, indexing 92% of core reproductive biology journals (e.g., Human Reproduction); Web of Science: Tracked citation networks, particularly for translational studies linking SP proteins to ovarian function; Scopus: Captured regional journals (e.g., Reproductive Sciences) and conference proceedings.
②. Keyword optimization
Boolean operators and adjacency commands refined the search: (“seminal plasma” OR “seminal fluid proteome”) AND (“endometrial receptivity” OR “decidualization” OR “ovulation induction” OR “luteal phase”).
Temporal filters: Limited to English articles (2000–2025), with weighted relevance for 2015–2025 publications.
Search alerts: Monthly updates via database auto-notifications (last update: September 2025).
2. Screening process
①. Initial triage
Deduplication: Automated removal of 167 duplicates using EndNote X20 (match
criteria: DOI + title + author overlap
Title/abstract screening: Two independent reviewers applied exclusion criteria: (a) excluded: animal-only studies (n = 412), non-peer-reviewed preprints (n = 89); (b) retained: 342 articles with human/mechanistic focus.
②. Full-text evaluation
Anonymized review: Discrepancies resolved by a third reviewer (kappa score: 0.81).
Exclusion rationale: “Incomplete data” was the most frequent reason for exclusion, with 98 cases. “Non-controlled trials” accounted for 72 exclusions, while “Low-impact reviews” represented 45 exclusions.
Pool: 127 studies met the criteria.
3. Inclusion criteria
①. Study types
Mechanistic investigations: Required molecular validation (e.g., mass spectrometry for protein identification).
Clinical studies: Mandated randomized controlled trials (RCTs) or cohort studies
with
Reviews: Only included if published in journals with a 5-year impact factor
(JCR)
②. Quality thresholds
GRADE assessment: Level 1 evidence prioritized (e.g., multicenter RCTs with CONSORT compliance).
Risk of bias: Evaluated via the Newcastle-Ottawa Scale for observational studies.
4. Supplementary methods
①. Snowball sampling
Backward reference tracing of 19 seminal papers (e.g., Robertson, 2005 [3]).
Forward citation tracking via Scopus (identified six newer studies).
②. Controversial findings
Established an “adversarial dataset” (n = 23) for sensitivity analysis.
Contacted corresponding authors for raw data (response rate: 38%).
SP was secreted by epithelial cells in the male urethra, urethral bulb, tail
epididymis, prostate gland, and seminal vesicles. SP was rich in various organic
and inorganic components necessary for pre-fertilization and embryonic
development, including amino acids, proteins, sugars, lipids, ions, enzymes,
immunoglobulin, and hormones [4]. SP contained a large amount of active signaling
substances that play roles in immune regulation and the regulation of biological
information. These active signaling substances include tumor necrosis
factor-
Seminal extracellular vesicles (SEVs) are important novel biological information carriers in the SP. SEVs are secreted by the apical plasma of testicular supporting cells and various male reproductive tract cells, and are mainly divided into prostatic vesicles and epididymal vesicles according to their sources. SEVs are produced as budding particles and contain bioactive substances from various cellular sources, including DNA, mRNA, microRNAs (miRNAs), lipids, and proteins [6]. The types and contents of the SEVs are related to the physiological or pathological state of the body and serve as biomarkers for disease diagnosis and carriers for targeted drug therapy [7]. The SP contains a large number of stable and enriched miRNAs. RNA sequencing and high-resolution mass spectrometry methods have made significant breakthroughs in the in-depth characterization of SEVs. Indeed, the roles of various miRNAs in male reproduction in SEVs have been reported in this study [8]. Studies have also reported the roles of miRNAs in the proliferation and migration of female uterine epithelial cells, endometrial vascular remodeling, and the impact of miRNAs on endometrial receptivity [9, 10]. However, research on the regulatory roles of extracellular vesicles and miRNAs in the FRT remains limited [11].
When semen enters the FRT and begins to move, the semen may activate inflammation and an immune response via SEVs [12]. The SP can regulate a series of biological changes in various parts of the FRT, thereby forming an endometrial environment suitable for embryo implantation and continued pregnancy.
The cervix is the main site where semen deposits first in females after sexual
intercourse. A large number of neutrophils are recruited to the cervix
approximately 1 hour later after being exposed to major bioactive substances in
the SP, such as TGF-
The SP ascends and contacts the endometrium under the peristaltic contraction of
the uterus and the selective passage of cervical mucus. Moreover, the SP
stimulates endometrial tissue to produce inflammatory reactions similar to those
of the cervix. Tregs migrating into the uterus can help the maternal immune
system accept the embryo, support blood vessel remodeling, and improve pregnancy
outcomes. Macrophage activation plays an important role in establishing pregnancy
and reducing the risk of adverse pregnancy outcomes [16, 17, 18]. Meanwhile,
infiltrating inflammatory cells can spread into the uterine cavity and penetrate
between the endometrial epithelium and stromal cells; thus, stimulating the
recruitment of white blood cells, cell proliferation, endothelial cell migration,
and gene expression related to epithelial cell and stromal fibroblast vitality,
including TNF-
In addition to affecting the physiological functions of the cervix and uterus,
semen can also affect ovarian function by promoting ovulation and corpus luteum
formation [25]. This process occurs through a unique counter–current exchange
mechanism. Prostaglandins, TGF-
Enzymatic barrier penetration: The prostate-specific antigen (PSA) in the SP
hydrolyzes threonine-serine bonds in cervical mucin MUC5B, increasing the
mucus pore diameter from 0.2 µm to 0.6 µm and reducing sperm
penetration resistance by 62%; immunomodulatory switch: zinc ions activate
the TLR4/NF-
During the critical window of fallopian tube microenvironment programming (2–24 hours post-ovulation), several key physiological parameters are dynamically regulated to optimize conditions for fertilization. The ciliary beat frequency is increased from 8 Hz to 12 Hz, which enhances gamete transport efficiency by approximately 50%, facilitating timely sperm-oocyte interaction. Concurrently, luminal pH is precisely maintained at 7.8 through bicarbonate (HCO₃⁻) secretion mediated by cystic fibrosis transmembrane conductance regulator (CFTR) activation; this alkaline environment triggers sperm hyperactivation, a crucial step in preparing sperm for penetration of the zona pellucida. Additionally, reactive oxygen species (ROS) levels are tightly controlled by superoxide dismutase (SOD), which sustains a safe concentration range of 0.2–0.5 nM, thereby preventing oxidative damage to the oocyte and preserving its developmental competence. Together, these coordinated regulatory mechanisms create a highly optimized microenvironment that supports successful fertilization and early embryonic development (Table 1).
| Parameter | Regulatory effect | Fertilization significance |
| Ciliary beat frequency | Increased from 8 Hz to 12 Hz | Enhanced gamete transport efficiency by 50% |
| Luminal pH | HCO3⁻ secretion via CFTR activation → pH 7.8 | Triggered sperm hyperactivation |
| ROS | SOD maintained a 0.2–0.5 nM safe window | Prevented oocyte oxidative damage |
CFTR, cystic fibrosis transmembrane conductance regulator; ROS, reactive oxygen species; SOD, superoxide dismutase.
High-speed atomic force microscopy documented an increase in flagellar waveform frequency from 3 Hz to 12 Hz [29].
Calcium oscillation initiation: seminal phospholipase A2 (PLA2) stimulates
ATP secretion from oviductal epithelium
The female reproductive tract maintains temporary immune protection through
three phases. In the first 0–6 hours (acute phase), transforming growth
factor-beta (TGF-
| Phase | Core mechanism | Biological outcome |
| Acute (0–6 h) | TGF- |
Inhibited neutrophil infiltration |
| Maintenance (6–72 h) | HLA-G induced CD4+ → Treg differentiation (FOXP3+) | Extended sperm survival to 72 hours |
| Termination | Macrophages cleared residual components via CD206 | Prevented chronic inflammation |
TGF-
Protease network activation: Oviductal alkalization (pH 7.8) activates
trypsinogen
SP was redefined as an active biological programmer. Future ART studies require personalized strategies based on seminal composition profiling [31].
ART refers to the medical technology that provides infertile couples a higher chance of becoming pregnant using medical aids. ART includes artificial insemination, in vitro fertilization–embryo transfer (IVF–ET), and its derivative technologies. IVF–ET refers to the process of retrieving oocytes from the woman and sperm from the man, fertilizing the oocytes in a laboratory dish to create an embryo, and then transferring the embryo into the uterus to achieve pregnancy. Unlike natural pregnancies, the absence of male SP during IVF–ET may be a contributing factor to the clinical pregnancy outcomes of IVF–ET.
A study conducted a clinical RCT on the effect of SP on pregnancy outcomes in assisted reproductive therapy [32]. The study performed high vaginal seminal fluid infusion on women receiving IVF–ET treatment 36–48 hours before embryo transfer. The study used spousal-derived semen, while the control group did not receive any pre-infusion. The experimental results showed a significant increase in embryo implantation rate in the experimental group, and this effect was not related to the patency of the female fallopian tubes. This suggests that SP improves pregnancy outcomes by regulating the function of the female endometrium. A double-annonymized randomized controlled parallel trial showed that injecting spouse-derived semen into the cervix and posterior vaginal fornix after female oocyte retrieval could improve clinical pregnancy rates compared to saline infusion in IVF–ET or intracytoplasmic sperm injection (ICSI) treatment [33]. However, the difference did not reach statistical significance, which may be related to the small sample size included in the study. Similar results were also obtained in another study [34]. Compared with the culture medium infusion group, the SP infusion group demonstrated higher patient embryo implantation and clinical pregnancy rates, suggesting the potential of SP to improve early pregnancy outcomes. The study indicated that SP can significantly enhance embryo implantation rates in IVF, achieving statistically significant effects in ART [35]. The study suggested that in clinical RCTs using uterine infusion of physiological saline as a control group during the IVF treatment cycle, the infusion of partner seminal fluid has no significant promoting effect on female reproductive outcomes. The intervention measure of the experimental group in this study was to perfuse diluted SP [36]. Due to differences in the concentrations of individual SP substances and the concentration-dependent inflammatory response of the FRT to male SP-derived substances, the molecular concentration in diluted SP from some individuals may not reach levels sufficient to produce clinical effects [37]. The confidence interval for the research results was wide; thus, clinically relevant differences between the two groups cannot be confidently excluded based on this study. This may also explain why the study reached different conclusions than previous research.
To further clarify the impact of SP intervention on the outcome of IVF treatment, the study included eight clinical RCTs totaling 2128 assisted reproductive therapy cycles for meta-analysis [38]. The results showed that spousal SP intervention could effectively improve the clinical pregnancy rate of IVF treatment compared with the control group receiving saline infusion or no intervention. The study included seven RCTs totaling 2204 assisted reproductive therapy cycles for the meta-analysis [39]. The results also showed that the clinical pregnancy rate in the SP intervention group was significantly higher. However, the study included 11 RCTs totaling 3215 assisted reproductive therapy cycles for the meta-analysis [40]. The results showed that although local application of spousal SP in the FRT had the potential to improve the clinical pregnancy rate in patients undergoing IVF/ICSI/freeze-thaw embryo transfer, the quality of evidence was low or extremely low [12]. This may be due to differences in SP exposure methods across studies, leading to different clinical outcome indicators and heterogeneity in clinical outcome measurement standards. These inclusion and exclusion criteria led to poor-quality evidence on clinical outcomes and methodological heterogeneity.
SP consistently induced immune cell recruitment (e.g., CD4+/CD8+ T cells, antigen-presenting cells) in the FRT across non-human primates and humans, enhancing mucosal vaccine responses. Meanwhile, SP proteins (e.g., heparin-binding proteins, zinc-binding proteins) regulate sperm capacitation, the acrosome reaction, and chromatin condensation in both humans and animals, with conserved ligand-binding mechanisms[13, 19]. Moreover, SP exposure triggers inflammation-like responses and tissue remodeling in the cervix, a conserved site of immune interaction.
While SP improved IVF outcomes in some studies, others reported no significant impact on embryo implantation rates, possibly due to differences in SP protein composition or exposure timing. The use of SP in intra-uterine insemination (IUI) showed conflicting results: some trials reported increased pregnancy rates, while others found no benefit over sperm-only preparations.
Current research reveals SP-mediated recruitment of CD8+ T cells to lymph nodes within the female reproductive tract, as demonstrated in non-human primate models. Concurrently, cross-species biochemical analyses indicate that heparin-binding proteins critically regulate sperm capacitation processes. However, significant knowledge gaps persist: the long-term impact of SP exposure on fetal-maternal immune tolerance during gestation remains poorly characterized due to limited longitudinal human cohort data. Furthermore, the absence of standardized protocols for optimizing SP protein ratios in ART formulations impedes clinical translation and outcome reproducibility. These unresolved questions highlight critical intersections between reproductive immunology and clinical fertility practice requiring systematic investigation [37].
TGF-
This study revealed that SP exposure before IUI did not significantly improve live birth rates [25], suggesting benefits might be limited to specific subgroups (e.g., thin endometrium or immune dysfunction).
SP presents three key clinical considerations in reproductive medicine: (1) It
transmits human immunodeficiency virus (HIV), hepatitis B virus (HBV), and human papillomavirus (HPV) at higher rates than sperm cellular components due to
elevated viral loads, necessitating rigorous donor screening and viral
inactivation; (2) Its proteome exhibits
| Risk category | Risk category transmission | Limitations |
| Pathogen transmission | HIV, HBV, and HPV were transmissible via SP (viral load |
Strict screening + viral inactivation |
| Inter-individual variability | Personalized SP component analysis | |
| Proinflammatory risk | High PGE2 concentrations triggered abnormal uterine contractions in |
Controlled SP dose/exposure timing |
SP, seminal plasma; HIV, human immunodeficiency virus; HBV, hepatitis B virus; HPV, human papillomavirus; PGE2, prostaglandin E2.
SP exosomes (e.g., miR-34c-5p) were internalized by endometrial cells,
activating the Wnt/
In the assisted reproductive therapy cycle, local stimulation of the reproductive tract of the patient with spousal-sourced SP on the day of oocyte collection or embryo transplantation may increase clinical pregnancy rates, while the impact on outcome indicators, such as embryo implantation rate, continuation implantation rate, live birth rate, miscarriage rate, and fetal birth weight, requires further clarification through larger sample experiments. Further clinical exploration is needed to determine the specific application components, methods, and timing of using spousal SP as an auxiliary reproductive therapy.
SP is rich in various nutrients and signaling molecules, providing essential support for sperm development and maturation. SP regulates the biological functions of the female reproductive system through direct contact with the FRT. Extracellular vesicles and miRNA in SP are important novel biological information carriers. Based on existing research, the SP exerts a systematic, multifaceted functional regulatory effect on FRT cells and tissues. The SP provides the biological foundation for the migration and implantation of sperm toward the distal end of the fallopian tube and of the fertilized oocyte toward the endometrium. The regulatory effect of the SP on female reproduction has been validated in assisted reproductive therapy, but its clinical efficacy remains unclear. SP is rich in ingredients, but the main active substances regulating female reproduction remain uncertain. Moreover, the specific signaling mechanisms that exert their effects have yet to be fully revealed. The exact timing and methods of the clinical application of SP in assisted reproduction require further exploration.
YS: design of the work, literature search of the work; LP: study conception. Both authors contributed to editorial changes in the manuscript. Both authors read and approved the final manuscript. Both authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.
Not applicable.
Not applicable.
This research received no external funding.
The authors declare no conflict of interest.
References
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