Search Results (1,409)

The weaning-to-estrus interval (WEI) is an important indicator of sow reproductive performance, yet the mechanisms underlying post-weaning anestrus in Tibetan sows remain unclear. In this study, multiparous Tibetan sows were classified into an estrus group (FQ) and an anestrus group (WQ) based on estrus status after weaning. Serum reproductive hormones, hematological parameters, gut microbiota (16S rRNA sequencing), and fecal metabolites (untargeted metabolomics) were analyzed. Compared with the FQ group, the WQ group showed significantly lower estradiol (E₂) and higher progesterone (P) levels (p < 0.01), along with a decreased proportion of neutrophils and an increased proportion of lymphocytes (p < 0.05). No significant differences in alpha diversity were observed, whereas PLS-DA revealed differences in microbial community structures between groups. LEfSe analysis indicated that Methanobrevibacter and Acinetobacter were enriched in the FQ group, whereas Muribaculaceae and Prevotella were enriched in the WQ group. Differential metabolites were mainly involved in amino acid and lipid metabolism and enriched in pathways related to steroid hormone biosynthesis, oocyte maturation, and tryptophan metabolism. These findings suggest that post-weaning anestrus may be associated with endocrine imbalances, immune changes, and gut microbiota–metabolite interactions. They may provide a basis for future studies in Tibetan pig breeding and genetic improvement. Full article

Background and Objectives: Endometriosis is a multifactorial gynecological condition associated with impaired fertility; however, its impact on embryo competence remains incompletely understood. This study aimed to evaluate embryo competence through a stepwise analysis of IVF outcomes across the developmental continuum, while also comparing patients with endometriosis and controls. Materials and Methods: A retrospective observational study was conducted, including 160 patients undergoing IVF, comprising 55 patients with endometriosis and 105 controls. Clinical and embryological data were analyzed sequentially across key developmental stages, including oocyte retrieval, metaphase II (MII) oocyte formation, fertilization (2PN), embryo development, and euploidy in a subgroup undergoing preimplantation genetic testing for aneuploidy (PGT-A). Stage-specific efficiency rates were calculated, and correlations between early- and late-developmental parameters were assessed. In addition, comparative analysis between groups was performed. Results: A progressive decline in developmental efficiency was observed across the IVF continuum, with approximately one-quarter of retrieved oocytes reaching the embryo stage and only a small proportion ultimately resulting in euploid Blastocysts. Strong positive correlations were identified among early-stage parameters, particularly retrieved oocytes, MII oocytes, and embryo yield (r = 0.77–0.96, p < 0.001), indicating that ovarian response and oocyte maturity significantly influence downstream outcomes. However, efficiency-based parameters showed limited predictive value for chromosomal competence. A moderate association was observed between MII oocytes and euploid Blastocysts (r = 0.58), whereas the relationship between embryo number and euploidy remained weak. Comparative analysis revealed no statistically significant differences between the endometriosis and control groups across the evaluated embryological parameters (p > 0.05 for all comparisons), suggesting that sequential analyses may provide complementary insight beyond direct comparisons. Conclusions: IVF outcomes follow a sequential developmental trajectory with a progressive decline in efficiency across stages. In endometriosis, early developmental competence appears to be affected, while chromosomal competence remains relatively preserved. Full article

Capacitation is a key maturation process that enables spermatozoa to acquire fertilizing ability and can be induced in vitro using capacitation media. Because capacitation protocols differ markedly among laboratories, we compared three compositionally distinct Hepes-, Tris-, and TALP-based media. This study was performed in boar spermatozoa using 3–6 biological replicates of pooled ejaculates depending on the assay, with 46 ejaculate samples from 12 boars in total. The aim was to determine whether such non-standardized conditions differentially affect signaling pathways leading to capacitation and thereby influence the detection of commonly used capacitation markers. We found clear differences among the tested media. All three induced capacitation-associated events, but their functional and molecular effects were not equivalent. The Hepes-based medium supported sperm motility most effectively, increasing total and progressive motility to 60.0% and 48.7%, respectively, after 1 h of incubation and maintaining the highest motility throughout the incubation period. In contrast, the Tris-based medium maintained lower but relatively stable motility, whereas the TALP-based medium showed a rapid decline in total motility from 53.1% to 15.2% during the first hour. The TALP-based medium induced the highest and most sustained protein kinase A (PKA) activity, reaching 0.047 U/mL at 0 h and 0.040 U/mL after 3 h, whereas the Hepes- and Tris-based media showed lower and less sustained activity ranging from 0.003 to 0.030 U/mL during incubation. In addition, distinct patterns of protein tyrosine phosphorylation were observed depending on the medium used. In particular, the TALP-based medium containing bicarbonate and bovine serum albumin (BSA) and the Hepes-based medium with the highest BSA concentration were associated with the highest levels of total protein tyrosine phosphorylation. Phosphoproteomic analysis further revealed condition-specific phosphorylation events, indicating that sperm maturation is dynamically regulated by the surrounding molecular environment. In contrast, no significant differences were detected in oxidative phosphorylation or in electron transport system complexes among the tested media. These findings show that differences in capacitation media composition, particularly in bicarbonate and BSA content, can markedly alter signaling outcomes and the interpretation of capacitation markers, with important implications for reproductive technologies and experimental standardization. Full article

Oocyte maturation is a pivotal event in teleost reproduction that directly determines egg quality, fertilization success, and the developmental competence of early embryos. However, the transcriptional and post-transcriptional regulatory mechanisms operating within oocytes during maturation in marine teleosts remain poorly understood. In the present study, the orange-spotted grouper (Epinephelus coioides), an economically important marine aquaculture species, was used as a model. Oocytes at four distinct maturation stages were obtained by microscopically removing the surrounding follicular layers, followed by integrated mRNA-seq and miRNA-seq analyses to characterize the molecular regulatory landscape underlying oocyte maturation and hydration. The results showed that, as maturation progressed, oocyte diameter and wet weight increased significantly, accompanied by a marked decrease in Na⁺ content, a significant increase in K⁺ content, and the continuous accumulation of most free amino acids, indicating the gradual establishment of an osmotic basis favorable for oocyte hydration. Transcriptomic analysis further revealed extensive transcriptional remodeling during both the early and late phases of maturation. Differentially expressed genes were significantly enriched in pathways related to oocyte meiosis, cytokine signaling, lipid metabolism, DNA replication, cell cycle regulation, ribosome biogenesis, spliceosome function, oxidative phosphorylation, and mitochondrial activity, suggesting that oocyte maturation is a dynamic process characterized by a shift from basal growth maintenance to metabolic reprogramming, maternal transcript remodeling, and terminal maturation responses. miRNA profiling identified a large number of stage-specific differentially expressed miRNAs, including let-7d-5p, miR-22a-3p, and novel-miR-20/27/118, whose predicted target genes were mainly enriched in ribosome-related pathways, oxidative phosphorylation, DNA replication, transcriptional regulation, and signal transduction. Moreover, the miRNA–TF–mRNA regulatory network demonstrated that miRNAs may not only directly repress target genes, but also mediate hierarchical regulatory cascades through transcription factors, thereby coordinately participating in cell cycle progression, cytoskeletal remodeling, vesicular transport, and immune- and cell communication-related responses. Collectively, this study provides the first systematic temporal atlas of mRNA and miRNA regulation during oocyte maturation and hydration at the oocyte level in a marine teleost, thereby deepening our understanding of the molecular basis of meiotic resumption and egg quality formation, and offering valuable theoretical support for the optimization of artificial breeding and the identification of key molecular targets in grouper reproduction. Full article

Epimedium is a traditional Chinese tonic used to tonify the kidneys, enhance sexual function, and strengthen muscles and bones. However, the potential effects of Epimedium on the semen quality of Bama boars remain incompletely elucidated. The objective of this study was to evaluate the effects of dietary Epimedium ultrafine powder (EP) supplementation on the semen quality of Bama boars and to explore the underlying mechanisms. The objective of this study was to evaluate the effects of dietary EP supplementation on the semen quality of Bama boars and to explore the underlying mechanisms. Eighteen healthy, sexually mature adult male Bama boars were randomly divided into three groups (n = 6) and fed either a basal diet (CON) or the basal diet supplemented with 0.3% (EP3) or 0.5% (EP5) Epimedium ultrafine powder for five weeks. This study employed enzyme-linked immunosorbent assay (ELISA), 16S RNA gene sequencing, non-targeted metabolomics (CON and EP5), and Spearman correlation analysis, among other methods. The results indicated that dietary Epimedium (0.3% and 0.5%) increased the levels of serum TP, FSH, and SOD and decreased the abnormal sperm rate and the levels of serum TBA, TNF-α, and IL-6. Among them, adding 0.5% Epimedium in the diet increased sperm motility and the levels of serum T, LH, and IgG. 16S rRNA gene sequencing analysis revealed that both 0.3% and 0.5% Epimedium supplementation reduced the abundance of Streptococcus. Specifically, the 0.3% dose decreased Prevotella abundance, while the 0.5% dose reduced Escherichia-Shigella abundance. PICRUSt2 analysis revealed that the pathways of phenylalanine, butanoate, biotin, and arachidonic acid metabolism were significantly enriched in the Epimedium group. A non-targeted metabolomics analysis identified that indole-3-acrylic acid, DL-tryptophan, 2-hydroxyphenylalanine, and propionylcarnitine showed significant upregulation after Epimedium supplementation. Spearman correlation analysis indicated that Streptococcus was negatively correlated with sperm motility and serum-related parameters (TP, T, LH, IgM, and IgG). Streptococcus and Escherichia-Shigella were negatively correlated with indole-3-acrylic acid, DL-tryptophan, and biotin. In conclusion, Epimedium has a positive impact on the seminal quality, reproductive hormones, and immune–antioxidant levels of Bama boars by regulating the composition and metabolites of the intestinal microbiota. Full article

Chronic exposure to fine particulate matter (${\mathrm{PM}}_{2.5}$) derived from residential wood combustion is a major environmental health concern in southern Chile and other cold-climate regions. Although ${\mathrm{PM}}_{2.5}$ has been linked to adverse reproductive outcomes, it remains unclear whether sustained exposure induces pregestational uterine alterations that compromise reproductive competence before the first pregnancy. This study evaluated the effects of chronic wood smoke-derived ${\mathrm{PM}}_{2.5}$ exposure on uterine morphology and molecular markers in nulliparous rats. A two-generation exposure model was used to assess cumulative effects. Second-generation (G2) female Sprague Dawley rats continuously exposed from conception were housed in filtered air (FA, control; $n=12$) or ${\mathrm{PM}}_{2.5}$-containing ambient air (NFA; $n=12$) until reproductive maturity (82 days). Uterine horns were analyzed by histology, planimetry, immunohistochemistry, immunofluorescence, and second harmonic generation microscopy. Markers of hypoxia, inflammation, extracellular matrix remodeling, angiogenesis, proliferation, apoptosis, and DNA repair were quantified. Chronic ${\mathrm{PM}}_{2.5}$ exposure increased hypoxia-inducible factor 1$\alpha$, tumor necrosis factor-$\alpha$, vascular endothelial growth factor A, and collagen types I, III, and IV, while transforming growth factor-$\beta$ expression and Ki-67-positive proliferating cells were reduced. Exposed rats showed increased apoptosis and decreased nuclear expression of ${\mathrm{O}}^6$-methylguanine-DNA methyltransferase, indicating impaired DNA repair capacity. Second harmonic generation imaging demonstrated increased collagen deposition with marked fibrillar disorganization. These findings indicate that chronic wood smoke-derived ${\mathrm{PM}}_{2.5}$ exposure induces hypoxia-driven structural and molecular alterations in the uterus of nulliparous rats before first pregnancy, including extracellular matrix remodeling, inflammatory imbalance, angiogenic dysregulation, reduced proliferation, and compromised DNA repair, suggesting early disruption of uterine homeostasis and increased susceptibility to adverse reproductive outcomes. Full article

We hypothesized that the application of digestate (D) to winter oilseed rapeseed would have the same effect on seed production as nitrogen fertilizer (N_f). It impacts yield by altering the mass of readily available N in the vegetative and reproductive periods of plant growth. This allows for a good yield forecast. This hypothesis was assessed in field experiments with rapeseed carried out in 2015/2016, 2016/2017, and 2017/2018. The experiment included three N fertilization systems (FSs): AN, based on ammonium nitrate (AN); D, with digestate-based N; DAN, using ²/₃ of digestate + ¹/₃ of AN—and five N_f doses: 0, 80, 120, 160, and 240 kg N ha⁻¹. The net seed yield increase due to N application was 1.44 t ha⁻¹ in the AN system, 1.53 t ha⁻¹ in D, and 1.77 t ha⁻¹ in DAN. The optimal N rates were 160, 250, and 224 kg N ha⁻¹. The N economy of winter oilseed rapeseed was assessed in two periods: vegetative—before anthesis (from the rosette stage to the beginning of anthesis, BBCH 30–BBCH 60) and reproductive (from the beginning of anthesis to full maturity, BBCH 60–BBCH 89). The mass of available N at the beginning of anthesis increased by 54.3% (151 kg N ha⁻¹ to 233 N ha⁻¹) and doubled (151 kg N ha⁻¹ to 302 kg N ha⁻¹) compared to its value at the rosette stage, taking into account the mass of N in the rapeseed canopy and its total mass in the soil/rapeseed continuum. No differences in NUE were found for the tested N carriers. The net increase in N available resources resulting from the application of N fertilizer was 55.1, 104.9, 102.8, and 93.0 kg N ha⁻¹ for respective plots fertilized with 60, 120, 180, and 240 kg N ha⁻¹. Three N indices were measured at the beginning of rapeseed anthesis—N in crop biomass (NAF, r = 0.87 ***), N balance (Nb60, r = 0.87 ***), and N released from soil resources (Ngain60, r = 0.79 ***)—and showed potential for seed yield (SEY) prediction. The linear dependence of SEY on these indicators indicates that the potential of the rapeseed canopy to effectively accumulate N during the vegetative growth was too low. This limitation was fully confirmed by analogous N management indicators, but developed for rapeseed during the seed-filling period. The key indicator of SEY at harvest was the N mass in rapeseed biomass (NAH, r = 0.95 ***). N from digestate acted as a slow-release fertilizer, giving it an advantage over ammonium nitrate. In summary, digestate is an optimal N carrier under conditions of average rapeseed yield. Full article

The effective growth and maturation of porcine oocytes in vitro are critical for advancing reproductive biotechnologies. In this study, we explored low-temperature plasma (LTP) treatment as a redox modulation strategy to enhance the survival and maturation of denuded porcine oocytes during in vitro primary culture in order to improve animal cellular health through innovative interventions. Freshly isolated oocytes were exposed to plasma treatment for different lengths of time and subsequently cultured under established in vitro conditions. Morphological and redox-related analyses showed that LTP treatment was associated with increased oocyte diameter, a higher first polar body extrusion rate, mitochondrial membrane potential changes, and altered intracellular and extracellular redox-related parameters. These beneficial effects exhibited a distinct time-dependent dose–response pattern. Furthermore, Western blot analysis showed altered expression of the EGFR/ERK signaling cascade and proteins such as Nrf2, suggesting that LTP treatment might participate in the regulation of maturation-related responses in porcine oocytes cultured in vitro by inducing redox-associated changes, along with alterations in EGFR/ERK-related signaling, Nrf2 expression, and molecules involved in maturation and apoptosis. Collectively, these findings highlight the positive role of LTP in supporting porcine oocyte maturation during in vitro primary culture and provide a promising approach for optimizing the in vitro primary culture of porcine oocytes. Full article

To unravel the genetic basis of economically critical reproductive traits in swine, we genotyped 839 sows from three commercial breeds (Duroc, Landrace, Yorkshire) using the Porcine Breeding Chip_plus 50K SNP array, and analyzed three key traits: total number born (TNB), number born alive (NBA), and number of healthy piglets (NHP). We integrated principal component analysis (PCA) for population structure, runs of homozygosity (ROH) detection, genome-wide association studies (GWAS), and GO/KEGG enrichment analysis. Phenotypically, Yorkshire sows exhibited superior and persistent reproductive capacity across parities 1–7 (peak TNB: 14.17 ± 2.82 at parity 4 based on N ≥ 3 data), Duroc sows had limited data with only parity 1 available (TNB: 9.44 ± 2.13), and Landrace sows showed moderate to high performance across parities 1–4 and 7, with peak TNB at parity 4 (17.08 ± 4.61). ROH analysis further revealed that short ROH fragments (1–5 Mb) were the most abundant category across breeds, while the majority of detected ROH were under 10 Mb in length. GWAS identified significant SNPs concentrated on chromosomes 1 and 2, and annotated candidate genes including AMH (ovarian reserve), IZUMO4 (embryo implantation), ACSBG2 (steroid synthesis), RFX2 (follicular maturation), and DOT1L (embryonic development). GO/KEGG enrichment highlighted pathways such as “histone methyltransferase activity” and “fatty acid biosynthesis”, which are critical for reproductive processes. This study clarifies breed-specific reproductive patterns and identifies key genetic loci/genes for porcine reproductive traits, providing molecular markers and a theoretical basis for improving swine reproductive performance via molecular breeding. Full article

Indonesia’s bird trade research has largely focused on songbirds, leaving other exploited taxa, such as hornbills, understudied. We address this gap by analyzing hornbill seizures in Indonesia (January 2015–December 2024) and online hornbill advertisements (January 2015–February 2025). We recorded 126 seizures and 231 advertisements revealing widespread illegal exploitation of all thirteen native Indonesian hornbill species, and endemic species from the Philippines and Africa. Trade involved live hornbills and hornbill beaks and casques. The prevalence of live trade suggests targeted poaching for the pet market is more extensive than previously documented, underscoring the need for further research and heightened enforcement. At least four endemic Philippines hornbill species were found in trade. The absence of CITES import records for these species indicates illegal international trafficking. At least two African endemic species were also observed for sale online in Indonesia underscoring the need for international monitoring and regulatory oversight to prevent over-exploitation. East Java and Jakarta emerged as principal trade hubs and Riau as a key transit point for hornbill parts entering international trafficking routes. Hornbills are particularly vulnerable to over exploitation because of their slow maturation, low re-productive rates, and complex ecological requirements. As such, Indonesia’s illegal hornbill trade demands targeted actions, including legal reform, strengthened enforcement capacity, and enhanced accountability of online platforms to curb these pressures and protect remaining populations. Full article

The chemical control of Leguminivora glycinivorella (Mats.) (Lepidoptera: Tortricidae) has been a major threat to the soybean industry in China over the years. Therefore, we need to develop green, safe, and environmentally friendly alternatives for pest control. Amine hormones, such as melatonin, represent an adjunct strategy for the green control of L. glycinivorella. We aimed to investigate the effects of exogenous melatonin on the development, survival, reproduction, nutrient accumulation, and cold tolerance of L. glycinivorella and to provide insights into the role of melatonin in insect adaptive regulation. Newly hatched L. glycinivorella larvae were fed on soybean pods immersed in solutions with different concentrations of exogenous melatonin. The developmental duration of larvae and pupae, survival rate, pupation rate, adult eclosion rate, body weight and length of larvae and pupae, nutrient composition of mature larvae, adult reproductive parameters, and supercooling and freezing points were measured. With increasing melatonin concentrations, the developmental durations of larvae and pupae were significantly prolonged, while the larval survival rate, pupation rate, and adult eclosion rate significantly decreased. The body weight and length of both larvae and pupae declined with increasing melatonin concentrations, reaching the lowest values in the 200 mg/L group. Melatonin treatment significantly reduced protein and lipid contents in mature larvae but significantly increased glycogen content. Reproductive parameters, including pre-oviposition period, oviposition period, fecundity, and female adult longevity, all decreased significantly with increasing melatonin concentrations. Additionally, melatonin treatment significantly lowered the supercooling point and freezing point of mature larvae. Exogenous melatonin significantly inhibits the growth, development, survival, reproduction, and nutrient metabolism of L. glycinivorella, yet enhances its low-temperature tolerance, suggesting that melatonin may serve as a potential tool for population management of L. glycinivorella through its dual regulatory role in insect physiology. Full article

Nerve Growth Factor (NGF), a member of the neurotrophin family, is currently regarded as a key regulator of ovarian physiology beyond its well-known neurotrophic functions. The mammalian ovary is one of the most highly innervated peripheral organs. Increasing evidence indicates that NGF and its receptors, TrkA and p75NTR, are widely expressed in ovarian tissues. Through the activation of the PI3K/AKT, MAPK/ERK, and PLCγ signaling pathways, NGF influences granulosa cell proliferation, steroidogenesis, and ovulation. Physiological levels of NGF are essential for primordial follicle activation, FSH receptor expression, and effective bidirectional communication between oocytes and surrounding somatic cells. As a result, NGF also regulates oocyte maturation and developmental competence. The disruption of NGF signaling can lead to serious health issues. Both low and high levels of NGF negatively affect folliculogenesis and fertility. Elevated intraovarian NGF results in sympathetic over-innervation, altered steroid production, and polycystic ovarian features. In addition, increased NGF expression has been linked to endometriosis and ovarian cancer progression. Clinical studies further suggest that follicular NGF levels may serve as indicators of ovarian reserve and reproductive outcomes in assisted reproduction. This narrative review synthesizes the current knowledge on NGF roles in ovarian physiology and disease. It highlights NGF’ dual functions as a central regulator of follicular dynamics, and as a potential biomarker and therapeutic target for common reproductive system diseases. Full article

Male infertility is an increasing global health concern associated with declining population growth. Mancozeb (MZ) exposure may induce reproductive toxicity through endocrine disruption and oxidative stress, impairing spermatogenesis. This study evaluated the effects of White Bualuang extract (WBE) on sexual behavior, testicular histomorphometry, and spermatogenic parameters in rats exposed to MZ. Thirty mature male rats were randomly assigned to the following five groups (n = 6): Control, MZ 500 mg/kg, MZ + 0.55 mg/kg WBE, MZ + 1.10 mg/kg WBE, and MZ + 2.20 mg/kg WBE, for 30 days. Sexual behaviors, relative testis weight, antioxidant properties, and histomorphometry parameters were determined. MZ-exposed rats had significantly decreased courtship behavior, seminiferous tubule diameter, and a tendency toward decreased spermatogenic cell numbers, along with enlarged interstitial spaces. However, pretreatment with WBE, especially at a dose of 0.55 mg/kg, showed improvements in courtship behavior and several histomorphometry parameters and was associated with increased Sertoli cell efficiency and spermatogenic organization compared with the MZ group. WBE showed potential to reduce lipid peroxidation (LPO) and advanced oxidation protein products (AOPP) in MZ-exposed rats, particularly, the 0.55 mg/kg dose improved courtship behavior and reproductive parameters, supporting further investigation of WBE as an antioxidant and potential functional supplement. Full article

Endometriosis is a chronic inflammatory disorder affecting approximately 10% of reproductive-age women, yet non-hormonal therapeutic options remain limited. This study investigates the role of the TLR4/NF-κB/NLRP3 inflammasome axis in endometriosis pathogenesis and evaluates the therapeutic potential of pharmacologic TLR4 inhibition. Ectopic endometriotic tissues, eutopic endometrium, and peritoneal fluid were collected from 15 patients with ovarian endometriosis and 15 control subjects. The endometriotic epithelial cell line 11Z was stimulated with LPS and ATP with or without the TLR4 inhibitor TAK-242. A murine endometriosis model was established in wild-type C57BL/6 and TLR4⁻/⁻ mice treated with TAK-242. Expression of TLR4, p-p65, NLRP3, caspase-1, cleaved caspase-1 (p20), GSDMD-N, IL-1β, PCNA, and CD31 was assessed by qPCR, Western blot, IHC, and ELISA. Ectopic lesions showed significantly elevated TLR4/NF-κB/NLRP3/IL-1β signaling compared with eutopic and control endometrium (all p < 0.05). Peritoneal fluid IL-1β was increased in patients, indicating a localized pelvic inflammatory response. In vitro, TAK-242 suppressed LPS/ATP-induced NF-κB/NLRP3 activation, pyroptosis, and IL-1β secretion (p < 0.05). Furthermore, the NLRP3-specific inhibitor MCC950 confirmed the essential role of NLRP3 inflammasome activation in IL-1β maturation. In vivo, TLR4 deletion or TAK-242 treatment reduced lesion weight, PCNA proliferation, and CD31 microvessel density (all p < 0.05). TLR4 inhibition blocks NF-κB nuclear translocation and subsequent inflammasome activation, suggesting a potential role in attenuating inflammation and angiogenesis. The TLR4/NF-κB/NLRP3 axis may drive endometriosis progression by linking innate immunity, inflammasome activation, pyroptosis, with possible involvement in angiogenesis warranting further investigation. Pharmacological inhibition of TLR4 attenuates lesion growth, supporting TLR4 as a promising non-hormonal therapeutic target for endometriosis. Full article

Seed initiation in Arabidopsis depends on regulatory transitions that begin before fertilization, yet these events are often treated as separate developmental episodes rather than as a connected sequence. Here, we synthesize evidence from megaspore mother cell (MMC) specification to endosperm cellularization and ask whether particular stage boundaries meet a narrow definition of developmental handover: a shift between dominant control logics, with detectable first-order consequences in the ensuing interval and acknowledged overlap across the boundary. This framework goes beyond canonical staging by distinguishing chronological succession from shifts in regulatory control, thereby clarifying where earlier states are expected to constrain later outcomes, which developmental boundaries are mechanistically well supported, and where further mechanistic resolution is most needed. We first examine how MMC singleness (restriction to a single reproductive founder cell per ovule primordium) emerges through coupled sporophytic restriction and local competence. We then consider how meiosis and female gametophyte maturation establish regulatory poise (an actively restrained and asymmetric mature female-gametophytic state), including cell-cycle restraint, companion-cell-restricted demethylation, and unequal gametic chromatin states that condition subsequent embryo and endosperm behavior. After fertilization, release of central-cell restraint, activation of an endosperm auxin program, and recruitment of maternal tissues together mark the onset of seed initiation. In this view, syncytial endosperm is an actively maintained developmental state shaped by parental dosage, epigenetic control, hormone signaling, and maternal interaction, whereas endosperm cellularization represents a regulated switch with seed-wide consequences. In Arabidopsis, the clearest handover is the mature female gametophyte-to-fertilization boundary, whereas the boundaries linking MMC specification to female gametophyte maturation and syncytial endosperm to cellularization remain provisional. Full article