Search Results (160)

The bearded dragon (Pogona vitticeps) is the most commonly kept pet lizard and a promising model organism for studies of sex determination and gonadal development. Despite its potential, the morphological basis of gonadogenesis in this species remains poorly characterized. Here, we provide a comprehensive histological characterization of gonad development in P. vitticeps using serial paraffin and semi-thin sections, supplemented by morphometric analyses. Gonadal ridges first appeared at stage S28 as bilateral thickenings of the coelomic epithelium, coinciding with primordial germ cell colonization; by S28/29, a recognizable cortex and medulla were already present. The first morphological differences between male and female gonads appeared at S29/30. In differentiating testes, well-defined testis cords with a central lumen formed rapidly, while the cortex became thin and retained only scattered germ cells. Testicular development was characterized by rapid lumen formation within the testis cords, resulting in their early transformation into seminiferous tubules, followed by elongation and coiling of the tubules, maintenance of a stable tubule diameter, and a transient mitotic arrest of germ cells, with proliferation resuming at stage S36. In differentiating ovaries, the cortex remained thick and multilayered, with a progressive increase in germ cell number reflecting active oogonial proliferation. The ovarian medulla expanded substantially, and from S36 onward, lacunae developed within the medullary cords. No meiotic cells were observed at any examined stage. These results provide an essential morphological framework for future molecular and experimental studies of sex determination and gonadal differentiation in this species and in squamates more broadly. Full article

Introduction: The European catfish (Silurus glanis) has expanded rapidly across Europe, significantly impacting native freshwater biodiversity. Despite its well-documented ecological and economic effects as a top predator, reproductive biology data from non-native populations remain scarce, limiting the development of effective management strategies. Objective: This study examines key reproductive traits, sex ratio, size at first maturity, spawning period, fecundity, and oocyte diameter, of an invasive European catfish population in the Lower Tagus River (LTR), Portugal, approximately 15 years after its establishment. Methodology: A total of 674 individuals were collected monthly from January 2022 to November 2023 using electrofishing, gill nets, baited hook-lines, and catches from professional fishermen. Sex and reproductive stage were assessed via gonadal analysis. Size at first maturity was estimated using logistic regression. Fecundity was determined by the gravimetric method, and oocyte stage and diameter were assessed histologically. The gonadosomatic index (GSI) was used to characterise the reproductive cycle. Results: The sex ratio was significantly female-biased (1.4:1). Size at first maturity (TL₅₀) was 72.9 cm TL for females and 68.8 cm TL for males. The spawning season extended from February to June, coinciding with water temperatures of 11–23 °C, with the highest GSI values reported to date for this species (GSI max = 22.5%). Histological analysis confirmed asynchronous oocyte development. Absolute fecundity ranged from 8364 to 319,000 oocytes per female and was positively correlated with total length and body weight. Mean mature oocyte diameter ranged from 1.50 to 3.21 mm. Conclusions: The European catfish in the LTR exhibits high reproductive plasticity, early maturity, a prolonged spawning season, and elevated fecundity, likely facilitated by warm water temperatures and abundant prey resources. Crucially, these parameters reveal earlier maturation and greater reproductive investment relative to native populations, demonstrating an extreme phenotypic plasticity characteristic of successful invasions in southern European aquatic ecosystems. These findings provide essential biological parameters for targeted management, including selective removal of large females, intensified fishing effort during the spawning season, and population monitoring to prevent compensatory reproductive responses. Full article

Sperm cryopreservation is an integral part of gene pool conservation programs for local poultry breeds. It is known that cryostress can cause significant changes in the expression profiles of microRNAs and their target genes—key players in spermatogenesis—in Gallus gallus domesticus. However, the transmission of these changes across generations remains poorly understood. The aim of this study was to evaluate the transgenerational epigenetic effects of rooster sperm cryopreservation on molecular genetics and histological parameters in the gonads of offspring (F1) during the embryonic (10 days) and postnatal (1 day) periods. The analysis included a comprehensive histomorphometric analysis of the gonads and a quantitative assessment of the expression of microRNAs (gga-miR-6701-3p, gga-miR-301a-5p) and their target genes (DMRT1, TGFB2), using qRT-PCR. Histological analysis of the gonads of 10-day-old embryos revealed early morphological abnormalities in the F1 (n = 10) offspring obtained from frozen–thawed semen (experimental group). It was found that day-old F1 chicks (n = 17) obtained from frozen semen had testes with a significantly reduced number of seminiferous tubules (−36%, p < 0.05) with an increased diameter (+22%, p < 0.05) and an increased number of undifferentiated gonocytes (+53%, p < 0.001) compared to chicks obtained from native semen (control group, n = 20). A decrease in the expression of DMRT1 and TGFB2 in the gonads of embryos (−48% and −29%, respectively, p < 0.05) and day-old chicks (−12% and −43%, p < 0.001 for TGFB2) was found, accompanied by an inversion of microRNA dynamics: miR-6701-3p was decreased and miR-301a-5p was increased. The obtained data provide important evidence of transgenerational effects in birds and contribute to the search for solutions to problems associated with maintaining sperm quality after cryopreservation, and indicate that cryopreservation does not simply reduce the level of molecular activity, but disrupts the ontogenetic regulatory program embedded in the genome. Full article

The widespread use of pesticides in agriculture has increased their levels in water bodies, threatening aquatic ecosystems. Among these, glyphosate and chlorpyrifos are widely used in Mexico and can cause toxic effects even at low doses. In aquatic organisms, early exposure to these pollutants can disrupt vital processes, such as sex determination, through oxidative stress. This study assessed the effects of exposure to environmental concentrations of glyphosate (100 μg/L), chlorpyrifos (1.5 μg/L), and their combination on zebrafish (Danio rerio) from early stages to 90 days post fertilisation (dpf). Survival was measured using Kaplan–Meier curves; lipid peroxidation was assessed by malondialdehyde (MDA); sex-related gene expression was measured by qPCR of selected genes at 30 dpf; and gonadal development was assessed by histology at 65 dpf. The results showed increased MDA levels in exposed fish. Glyphosate caused early toxicity and a higher proportion of undifferentiated fish, implying delayed sex determination. Chlorpyrifos induced oxidative stress and affected amh gene expression linked to masculinisation. Combined exposure reduced survival and altered gene expression and gonadal development. Exposure shifted the sex ratio toward males, suggesting that pesticide-induced oxidative stress may alter the expression of sex determination genes during early development. Full article

The present study describes the reproductive cycle of the razor clam (Solen marginatus) from the Ria Formosa lagoon in the Algarve region (southern Portugal), using histological preparations of gonads from samples collected monthly over an 18-month period, from January 2023 to June 2024. Simultaneously, the mean gonadal index (GI) was estimated and its relationship with fluctuations in seawater temperature and chlorophyll a concentration was examined. The reproductive cycle of S. marginatus showed a seasonal pattern, with a resting period between August and October, followed by the onset of gametogenesis in November, which lasted until March. Ripe individuals were observed between February–March and May, with the spawning period occurring primarily between May and July. The mean GI reflected the temporal variation in the gonadal cycle. Reproduction in this species was strongly influenced by fluctuations in seawater temperature, but was not significantly correlated with chlorophyll a concentration. The information gathered in this study is of utmost importance, as it enables the proposal of evidence-based management measures aimed at promoting the sustainable exploitation of this resource. According to these new findings, a closed season (June or July) prohibiting razor clam harvesting in the Ria Formosa lagoon between May and July is proposed. Full article

Background: Diets composed of various components have been shown to influence inflammatory diseases such as asthma. While most studies have focused on fiber-rich diets to investigate their effects on the immune system and, consequently, on asthma, little is known about the impact of sugar-rich diets, particularly when such diets are consumed over short periods of time. Methods: To investigate the short-term effects of a sugar-rich diet on allergic airway inflammation, A/J mice were fed either a standard diet or a sugar-enriched diet and subsequently sensitized and challenged with ovalbumin or PBS. Airway inflammation was assessed by bronchoalveolar lavage (BAL) cell analysis, including eosinophil counts and cytokine levels (IL-4, TNF-α, IL-33), and by lung histology (H&E for inflammatory infiltrate and PAS for mucus). Serum IgE levels were also measured. In addition, glucose tolerance, visceral and subcutaneous adipose tissue mass, and inflammatory markers in visceral adipose tissue were evaluated. Results: Short-term consumption of a sugar-rich diet induced glucose intolerance and expansion of adipose tissue, particularly visceral fat, independent of ovalbumin sensitization. Gonadal adipose tissue analysis revealed a shift toward M1 macrophage polarization, characterized by elevated TNF-α, IL-6, and IL-1β, increased leptin levels, and reduced adiponectin. In OVA-sensitized mice, the sugar-rich diet significantly exacerbated eosinophil infiltration in BAL, increased IL-4, TNF-α, and IL-33, and enhanced PAS-positive mucus accumulation and inflammatory infiltrates in the lung. Moreover, total serum IgE was significantly higher in allergic mice fed the sugar-rich diet compared with allergic mice on the standard diet. Importantly, in non-sensitized mice fed the sugar-rich diet, no pulmonary inflammation was detected by BAL, demonstrating that HSD alone does not induce asthma but amplifies allergic responses when sensitization is present. Conclusions: Our findings demonstrate that short-term consumption of a sugar-rich diet is sufficient to exacerbate, but not initiate, allergic pulmonary inflammation. From a translational perspective, reducing dietary sugar intake may represent a valuable adjuvant strategy in the management of allergic asthma. Full article

Monosex all-male culture of the giant freshwater prawn (Macrobrachium rosenbergii) maximizes aquaculture yield due to a male growth advantage, but direct hormonal treatment of grow-out populations poses significant food safety risks. This study evaluated the efficacy of dietary 17β-estradiol (E2) in inducing functional neo-females from a fully all-male postlarval population to support an indirect monosex seed production strategy. All-male postlarvae were fed diets supplemented with E2 at concentrations of 0, 50, 100, 150, and 200 mg/kg for 36 days, followed by a 150-day hormone-free post-treatment period to assess growth performance, feminization rates, and gonadal histology. E2 administration successfully induced feminization across all treatments, reaching a peak rate of 35.5% at 150 mg/kg, whereas the control group remained entirely male. During the 36-day treatment period, E2 supplementation transiently enhanced specific growth and survival rates but concurrently reduced feed conversion ratios. Notably, these physiological differences disappeared completely over the 150-day post-treatment phase. Histological assessments confirmed that E2-induced neo-females exhibited normal oogenesis, with gonadosomatic index (GSI) values and oocyte diameters similar to those of wild-caught females. This establishes a definitive, physiologically safe, and non-surgical protocol for producing the neo-female broodstock necessary to sustain high-yield commercial monosex populations. Full article

Epilepsy is associated with impaired reproductive function and testicular pathologies. Intermittent fasting (IF) is a nonpharmacological metabolic intervention with anti-inflammatory and antioxidant effects. This study investigated the protective effects of IF on testicular damage in a genetic absence epilepsy rat model (GAERS), focusing on histomorphology, oxidative stress parameters, and hormonal profiles. Testicular tissues from Wistar control (WC), Wistar + IF (WIF), GAERS control (GC), and GAERS + IF (GIF) groups (total n = 20; 5 rats per group) were evaluated using hematoxylin and eosin and Periodic Acid–Schiff staining. Apoptosis and spermatogenic cell integrity were assessed using caspase-3, P-element-induced wimpy testis (PIWI), and Deleted in Azoospermia-Like (DAZL) immunohistochemistry. Johnsen’s score, seminiferous tubule diameter, and epithelial thickness were quantified. Oxidative stress markers, including catalase, malondialdehyde, glutathione, myeloperoxidase, and superoxide dismutase, were measured using spectrophotometric methods, and serum testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels were determined using ELISA kits. The GC group showed significantly reduced Johnsen scores, tubular diameters, and epithelial thickness, along with disrupted basement membrane integrity and increased caspase-3 immunoreactivity. IF significantly improved histological parameters, restored basement membrane integrity, reduced apoptosis, and increased PIWI and DAZL expression in the GIF group. IF also ameliorated oxidative stress and elevated reproductive hormone levels, indicating positive modulation of the hypothalamic–pituitary–gonadal axis. In conclusion, IF reduces oxidative stress and preserves seminiferous tubules and hormonal function in genetic absence epilepsy, highlighting its potential as a supportive nonpharmacological approach to protect male reproductive health. Full article

Genes involved in sexual development have been identified in many teleost fishes, including the turbot, a flatfish of high commercial value in aquaculture. In this species, a major sex determination (SD) Quantitative Trait Locus has been identified, and Sox2 has been proposed as the SD gene. Although RT-PCR, qPCR, and transcriptomic analyses have been performed on turbot gonads, histological studies remain limited. Here, we examined the tissue-specific expression patterns of several sex-related genes in turbot using in situ hybridization on paraffin sections (SISH) of differentiated ovaries and testes of juvenile and adult specimens. Vasa, Foxl2, Amh, Sox2 and Sox17 transcripts were detected in both male and female gonads, whereas Cyp19a1a and Sox19 expression was restricted to the ovary; these results support previous gene expression analyses and suggest a role for these genes in gonadal development and reproductive functions in this species. SISH provides complementary information to molecular analyses by identifying the specific cell types expressing the sex-related genes analyzed in gonadal tissue, thereby offering a more comprehensive understanding of gonadal differentiation in turbot. Comparison with results reported for the gonads of other teleost species revealed similar tissue-specific gene expression patterns during sexual development. Full article

Haplosporidium edule is a haplosporidian parasite originally described in the common edible cockle (Cerastoderma edule) along the European Atlantic coast. In this study, we report the first detection of H. edule in the olive-green cockle (Cerastoderma glaucum) from the northern Adriatic Sea, representing both a novel host record and a new geographic occurrence. During a cross-sectional study conducted in May 2019, 90 C. glaucum specimens were collected from three lagoon sites in northeastern Italy. Histological examination of soft tissues revealed haplosporidian developmental stages, including plasmodia, sporoblasts and mature spores, within connective tissues of the mantle, digestive gland, gills and between gonadal tubules in eight individuals from the Goro Lagoon. Molecular characterization based on a fragment of the small subunit ribosomal DNA showed high similarity with the previously published H. edule sequence. Host identification was confirmed through cytochrome c oxidase subunit I barcoding together with morphological and histological analyses. These findings indicate that H. edule has a broader host range than previously recognized. Although prevalence was relatively low, the detection of this parasite in a new host species and geographic area highlights the importance of continued surveillance, particularly in the context of climate change, shellfish translocations and the expansion of aquaculture activities. Full article

Background/Objectives: Sex differences in lung cancer incidence and outcomes are well recognized, yet the relative contributions of sex chromosomes and gonadal sex remain incompletely defined. We aimed to disentangle chromosomal complement and hormonal sex in urethane-induced lung tumorigenesis using the Four Core Genotypes mouse model. Methods: Mice (6–8 weeks old) with independently varied chromosomal complement (XX vs. XY) and gonadal sex received urethane (1 g/kg body weight) weekly for 10 weeks and were evaluated after a 20-week latency period. Tumor multiplicity, tumor area, normalized tumor burden, and Ki-67 proliferation indices were quantified histologically. Hepatic Cyp2e1 expression was measured to assess carcinogen bioactivation. Tumor mutations were analyzed by Sanger sequencing. RAS Q61R immunoreactivity and ERK phosphorylation were evaluated to assess oncogenic signaling. Bronchoalveolar lavage fluid cellularity was analyzed. Survival was monitored. Statistical analyses tested the main effects of chromosomal complement, gonadal sex, and their interaction. Results: Tumor multiplicity (p = 0.0729), tumor area (p = 0.5302), normalized tumor burden (p = 0.5316), and Ki-67 indices (p = 0.6551) did not differ among genotypes. Hepatic Cyp2e1 expression was comparable across groups (genotype p = 0.076; treatment p = 0.445). Sanger sequencing confirmed canonical Kras Q61R mutations. Anti-RAS (Q61R) immunohistochemistry revealed a significant genotype effect on mutant RAS expression (F(3,23) = 3.48, p = 0.032), with the highest H-scores observed in XYF mice compared with male gonadal genotypes; ERK phosphorylation did not differ. Bronchoalveolar lavage fluid analysis revealed increased lymphocytes after urethane exposure without genotype-dependent effects. Survival differed significantly, with XX females demonstrating prolonged survival relative to XY males. Conclusions: Sex influenced survival independently of tumor burden, indicating that sex-associated differences in lung cancer outcomes are likely driven by systemic or microenvironmental factors rather than tumor-intrinsic growth mechanisms. Full article

Pure mediastinal yolk sac tumor is an uncommon and aggressive malignant germ cell neoplasm that presents considerable diagnostic difficulties owing to its pronounced clinical and morphological variability. Mediastinal yolk sac tumors, in contrast to their gonadal equivalents, typically occur at later stages, are typically associated with mixed germ cell components, and have a diverse array of histologic patterns that may resemble both germ cell and somatic malignancies. Accurate identification of these types of cancer is essential since diagnostic misclassification may significantly impact treatment and prognosis. This review provides a comprehensive overview of the morphologic spectrum of mediastinal yolk sac tumor, with emphasis on both classic and variant histologic patterns, including reticular, solid, glandular, papillary, hepatoid, and other less common growth forms. The immunohistochemical correlations of these patterns and their role in resolving diagnostic dilemmas are discussed, along with key differential diagnoses encountered in small mediastinal biopsy specimens. Particular attention is given to the limitations of limited tissue sampling, the impact of post-chemotherapy morphologic changes, and the potential for misinterpretation in this challenging anatomic site. By integrating morphologic features with clinical, radiologic, and laboratory findings, this review aims to enhance diagnostic accuracy and improve recognition of mediastinal yolk sac tumor across its diverse presentations. Full article

The Manila clam Ruditapes philippinarum is a commercially important bivalve worldwide, with China being the leading producer. While the reproductive biology of this species has been extensively studied in its native or long-established ranges, knowledge of how populations cultured from non-native seed sources adapt their reproductive cycles to new environmental conditions remains limited. In this observational study, we investigated the annual reproductive cycle of a Manila clam population originating from subtropical waters (Zhejiang Province, Southern China) that was cultured in temperate aquaculture grounds in Zhuanghe Bay, Northern China. Monthly histological examination of 50 clams demonstrated that the gametogenic cycle synchronized between male and female clams. Gametogenesis started in March when seawater temperature exceeded 5.7 °C, and most gametes matured by May. A distinct bimodal spawning pattern was observed: a minor spawning event occurred from May to July, followed by a major spawning phase from September to November after a one-month gonadal recovery period in August. The condition index (CI), analyzed monthly in 30 clams, effectively reflected reproductive stages, increasing during gametogenesis and declining sharply during spawning, with its amplitude indicating spawning intensity. Seawater temperature was identified as the primary regulatory factor driving reproductive development from gametogenesis to spawning, while food availability (indicated by chlorophyll a concentration) played a crucial role in supporting gonadal recovery during summer. These results align with observations in other temperate populations, demonstrating that subtropical-origin clams can successfully acclimate their reproductive cycles to temperate environmental conditions. This study provides the first comprehensive description of the reproductive biology of transplanted Manila clams in Northern China, offering critical benchmarks for optimizing hatchery production schedules and informing sustainable fishery management practices in the region. Full article

The gonadal development of Japanese eels (Anguilla japonica) plays a crucial role in the success of artificial breeding. Soy isoflavones, a class of phytoestrogens commonly found in aquafeeds, have shown potential in enhancing gonad development in fish. The present study evaluated the effects of dietary soy isoflavones on gonadal development, growth performance, histology, sex hormone levels, vitellogenin content, and expression of related genes in female Japanese eel broodstock. A 4-week feeding trial was conducted with 120 two-year-old female eels randomly assigned to four groups and fed diets containing 0 (C), 0.1 (L), 0.5 (M), and 0.9 (H) mg/g of soy isoflavones. The results indicated that gonadal development was enhanced in the M and H groups, as evidenced by a significantly higher gonadosomatic index (GSI) and increased oocyte cross-sectional area (CSA) in M group, and greater nutrient accumulation in both the M and H groups. The expression of er and cyp19a genes in the ovary was downregulated in the treatment groups, leading to decreased serum estradiol (E2) and increased testosterone levels. Furthermore, hepatic vtg gene expression was upregulated in the M and H groups, though VTG protein content remained unchanged, suggesting an initiation of vitellogenesis at the transcriptional level. In conclusion, dietary soy isoflavones at 0.5–0.9 mg/g provide an effective pretreatment strategy to enhance early ovarian development in Japanese eel broodstock, potentially improving their responsiveness to subsequent hormonal induction in artificial breeding programs. Full article

Propylparaben (PP) is a widely used preservative in cosmetics, pharmaceuticals, and food products, and its potential toxicity to non-target aquatic invertebrates remains a concern. This study used the freshwater snail Biomphalaria glabrata as a model organism to evaluate the toxic effects of PP through acute and chronic exposures at embryonic, newly hatched, and adult stages. Acute exposure experiments showed concentration-dependent mortality and developmental inhibition, with LC₅₀ values of 36.69 mg/L (embryos, 168 h), 33.48 mg/L (newly hatched snails, 96 h), and 57.05 mg/L (adults, 72 h). Chronic exposure of adult snails to 10–49 mg/L PP for 21 days significantly reduced growth and reproductive output, and no embryo masses were observed at concentrations ≥ 25 mg/L. Histological observations revealed progressive damage to the hepatopancreas and gonads. These results demonstrate that PP induces multiple toxic effects in B. glabrata, affecting survival, growth, reproduction, and tissue structure under both acute and chronic exposure conditions. The findings provide experimental evidence for evaluating the ecological risks of paraben contamination in freshwater ecosystems. Full article