Ovarian Follicular Development Research Articles

Reproductive health assessments in female polar bears: Anatomy, pathology, and diagnostic techniques

The reproductive success of polar bears (Ursus maritimus) in U.S. zoos is poor and the underlying causes of reproductive failure remain elusive. It is evident that new methodologies for evaluating fertility are needed, along with baseline information about species-specific reproductive anatomy and physiology. Between 2012 and 2024, 25 examinations of 17 female polar bears were conducted opportunistically, and included vulvar measurements, vaginal cytology, vaginoscopy, hysteroscopy with endometrial biopsy, and/or ultrasonography. Additionally, reproductive tracts (n = 10) harvested post-mortem were examined shortly after collection, allowing for inspection of anatomy ex vivo. The outcomes of these activities yielded detailed measurements and descriptions of reproductive anatomy. Vaginal cytology patterns demonstrated shifts in vaginal epithelial cell type associated with estrus and vaginoscopy enabled systematic evaluation of internal reproductive structures, including the vestibule, vestibulo-vaginal junction, urethral os, vaginal canal, and cervix. Hysteroscopy allowed visualization of the uterine endometrium and facilitated endometrial biopsy collection. Additionally, ultrasonography was utilized to identify ovaries in several bears, offering insights into ovarian dynamics and follicular development. Several abnormalities were noted during examinations of both in vivo and ex vivo tracts; these included clitoral hypertrophy, vaginal strictures, uterine polyps, endometritis, and cystic hyperplasia, although it is unclear if these aberrations significantly impacted fertility. Findings contribute to a better understanding of polar bear reproductive anatomy, highlight the utility of diagnostic techniques for monitoring reproduction, and elucidate potential causes of reproductive failure in polar bears.

Consumption of soya isoflavones improved polycystic ovary syndrome-associated metabolic disorders in a rat model.

Polycystic ovary syndrome is associated with increased risks for certain metabolic disorders such as insulin resistance, non-alcoholic fatty liver disease and suppressed ovarian follicular development. This study aimed to examine whether soya isoflavones (ISF) mitigate these polycystic ovary syndrome-associated metabolic disorders in a rat model. Weanling Sprague-Dawley female rats were randomly divided into six groups and were treated with either 0 or 83 µg/d dihydrotestosterone (DHT) to induce polycystic ovary syndrome and fed diets containing 0, 0·5, or 1 g ISF/kg diet for 8 weeks. DHT treatment increased food intake, body weight gain (P < 0·001), percentage of primordial follicles (60 % v. 50·9 %, P < 0·05) and accumulation of lipid droplets in the livers. It also elevated serum total cholesterol, free cholesterol, TAG, NEFA and leptin and hepatic total cholesterol and NEFA. Additionally, DHT treatment reduced the percentage of primary follicles (13·8 % v. 30·2 %, P < 0·05), ovary weight and length (P < 0·001), as well as insulin sensitivity (P < 0·01) compared with the Control. ISF intake at 1 g/kg reduced body weight gain, serum total cholesterol, free cholesterol, NEFA, leptin and hepatic TAG and DHT-induced insulin resistance (P < 0·01). ISF intake at both levels decreased DHT-induced lipid droplet accumulation in the livers and changes in the percentages of primordial and primary follicles. Dietary soya ISF alleviated DHT-induced body weight gain, insulin resistance and hepatic lipid droplet accumulation, as well as suppressed ovarian follicular development. This suggests that the consumption of soya foods or ISF supplements may be beneficial for individuals with polycystic ovary syndrome, mitigating the associated metabolic disorders such as diabetes and non-alcoholic fatty liver disease.

Downregulation of CASC15 attenuates the symptoms of polycystic ovary syndrome by affecting granulosa cell proliferation and regulating ovarian follicular development

Polycystic ovary syndrome (PCOS) is a type of follicular dysplasia with an unclear pathogenesis, posing certain challenges in its diagnosis and treatment. Cancer susceptibility candidate 15 (CASC15), a long non-coding RNA closely associated with tumour development, has been implicated in PCOS onset and development. Therefore, this study aimed to investigate the molecular mechanisms underlying PCOS by downregulating CASC15 expression in both in vitro and in vivo models. We explored the potential regulatory relationship between CASC15 expression and PCOS by examining cell proliferation, cell cycle dynamics, cell autophagy, steroid hormone secretion capacity, and overall ovarian function in mice. We found that CASC15 expression in granulosa cells derived from patients with PCOS was significantly higher than those of the normal group (P < 0.001). In vitro experiments revealed that downregulating CASC15 significantly inhibited cell proliferation, promoted apoptosis, induced G1-phase cell cycle arrest, and influenced cellular autophagy levels. Moreover, downregulating CASC15 affected the follicular development process in newborn mouse ovaries. In vivo studies in mice demonstrated that disrupting CASC15 expression improved PCOS-related symptoms such as polycystic changes and hyperandrogenism, and significantly affected ovulation induction and embryo implantation in pregnant mice. Overall, CASC15 was highly expressed in granulosa cells of patients with PCOS and its downregulation improved PCOS-related symptoms by influencing granulosa cell function and follicular development in mice.

Gonadotropin-Releasing Hormone (GnRH) and Its Agonists in Bovine Reproduction I: Structure, Biosynthesis, Physiological Effects, and Its Role in Estrous Synchronization.

GnRH is essential for the regulation of mammalian reproductive processes. It regulates the production and release of pituitary gonadotropins, thereby influencing steroidogenesis and gametogenesis. While primarily produced in the hypothalamus, GnRH is also produced in peripheral organs, such as the gonads and placenta. GnRH analogs, including agonists and antagonists, have been synthesized for the reproductive management of animals and humans. This review focuses on the functions of hypothalamic GnRH in the reproductive processes of cattle. In addition to inducing the surge release of LH, the pulsatile secretion of GnRH stimulates the pituitary gland to release FSH and LH, thereby regulating gonadal function. Various GnRH-based products have been synthesized to increase their potency and efficacy in regulating reproductive functions. This review article describes the chemical structures of GnRH and its agonists. This discussion extends to the gene expression of GnRH in the hypothalamus, highlighting its pivotal role in regulating the reproductive process. Furthermore, GnRH is involved in regulating ovarian follicular development and luteal phase support, and estrus synchronization is involved. A comprehensive understanding of the role of GnRH and its analogs in the modulation of reproductive processes is essential for optimizing animal reproduction.

Integrative proteomic and transcriptomic analysis in the female goat ovary to explore the onset of puberty

Puberty is considered a prerequisite for affecting reproductive performance and productivity. Little was known about molecular changes in pubertal goat ovaries. Therefore, we measured and performed a correlation analysis of the mRNA and proteins changes in the pre-pubertal and pubertal goat ovaries. The results showed that only six differentially expressed genes and differentially abundant proteins out of 18,139 genes and 7550 proteins quantified had significant correlations. CNTN2 and THBS1, discovered in the mRNA-mRNA interaction network, probably participated in pubertal and reproductive regulation by influencing GnRH receptor signals, follicular development, and ovulation. The predicted core transcription factors may either promote or inhibit the expression of reproductive genes and act synergistically to maintain normal reproductive function in animals. The interaction between PKM and TIMP3 with other proteins may impact animal puberty through energy metabolism and ovarian hormone secretion. Pathway enrichment analyses revealed that the co-associated key pathways between ovarian genes and proteins at puberty included calcium signalling pathway and olfactory transduction. These pathways were associated with gonadotropin-releasing hormone synthesis and secretion, signal transmission, and cell proliferation. In summary, these results enriched the potential molecules and signalling pathways that affect puberty and provided new insights for regulating and promoting the onset of puberty. SignificanceThis study conducted the first transcriptomic and proteomic correlation analysis of pre-pubertal and pubertal goat ovaries and identified six significantly correlated molecules at both the gene and protein levels. Meanwhile, we were drawn to several molecules and signalling pathways that may play a regulatory role in the onset of puberty and reproduction by influencing reproductive-related gene expression, GnRH receptor signals, energy metabolism, ovarian hormone secretion, follicular development, and ovulation. This information contributed to identify potential biomarkers in pubertal goat ovaries, which was vital for predicting the onset of puberty and improving livestock performance.

Systematic Review of the roles of Inositol and Vitamin D in improving fertility among patients with Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder among reproductive-age women. As a leading cause of anovulatory infertility, it complicates fertility treatments, including in vitro fertilization. The widely accepted 2003 Rotterdam diagnostic criteria for PCOS include sub-phenotypes based on variations in androgen excess, ovulatory dysfunction, and polycystic ovarian morphology. In this systematic review, we examined the impacts of inositol and vitamin D on fertility in PCOS. Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines, we used relevant keywords to comprehensively search databases including PubMed, Google Scholar, and MDPI. From an initial pool of 345 articles, 10 met the inclusion criteria. The articles suggest that vitamin D and inositol, particularly myo-inositol and D-chiro-inositol, may represent therapeutic options for PCOS. Vitamin D influences ovarian follicular development, glucose regulation, and insulin sensitivity. When combined with metformin therapy, it is associated with improved menstrual regularity and ovulation. Inositol is crucial for cellular signaling, energy metabolism, glucose regulation, and fertility. This systematic review underscores the importance of investigating inositol and vitamin D within a PCOS management strategy, given the disorder's prevalence and impacts on fertility and metabolic health. Although these agents show promise, additional research could clarify their mechanisms of action and therapeutic benefits. This review emphasizes the need for exploration of effective treatments to improve the quality of life among individuals with PCOS. Inositol and vitamin D represent potential options, but more studies are required to elucidate their roles in the management of this condition.

Effect of Curcuma longa maceration treatment on ovarian follicular development, serum oestradiol, uterine growth and vascularisation in female albino rats

Abstract Introduction Curcuma longa is a well-known medicinal plant with various health benefits. This study was designed to evaluate the administration of Indonesian C. longa maceration for its effect on promoting growth and development of the ovary and uterus before mating in female albino rats. Material and Methods A total of 15 female Sprague Dawley rats in their dioestrous phase were assigned into three different groups: the Control group (mineral water); the Cur-Low group (mineral water with 1% C. longa maceration) and the Cur-High group (mineral water with 5% C. longa maceration). The treatments were given for 20 days. Serum concentrations of follicle-stimulating hormone, oestradiol and progesterone were determined. After the sacrifice of the rats, ovary and uterine relative weight, uterine cornua diameter and length, uterine gland diameter (by histology), the number of primary, secondary, tertiary, and Graafian follicles, the number of corpora lutea and vascular endothelial growth factor (VEGF) expression in the ovary were measured. Uterine vascularisation was also evaluated. Results Administration of C. longa maceration significantly improved the relative weights of the uterus and ovary; uterine cornua diameter, length and vascularisation; uterine gland diameter; and expression of VEGF in the ovary. It also increased the number of tertiary follicles and corpora lutea, albeit not significantly. Follicle-stimulating hormone serum concentrations were lower in the administered rats. Conclusion Oestradiol and progesterone levels rose with C. longa maceration treatment. The maceration improved the reproductive organs of unmated rats and had potential to optimise the uterine environment for supporting pregnancy in order to produce high-quality offspring.

Local effect of allopregnanolone in rat ovarian steroidogenesis, follicular and corpora lutea development

Allopregnanolone (ALLO) is a known neurosteroid and a progesterone metabolite synthesized in the ovary, CNS, PNS, adrenals and placenta. Its role in the neuroendocrine control of ovarian physiology has been studied, but its in situ ovarian effects are still largely unknown. The aims of this work were to characterize the effects of intrabursal ALLO administration on different ovarian parameters, and the probable mechanism of action. ALLO administration increased serum progesterone concentration and ovarian 3β-HSD2 while decreasing 20α-HSD mRNA expression. ALLO increased the number of atretic follicles and the number of positive TUNEL granulosa and theca cells, while decreasing positive PCNA immunostaining. On the other hand, there was an increase in corpora lutea diameter and PCNA immunostaining, whereas the count of TUNEL-positive luteal cells decreased. Ovarian angiogenesis and the immunohistochemical expression of GABAA receptor increased after ALLO treatment. To evaluate if the ovarian GABAA receptor was involved in these effects, we conducted a functional experiment with a specific antagonist, bicuculline. The administration of bicuculline restored the number of atretic follicles and the diameter of corpora lutea to normal values. These results show the actions of ALLO on the ovarian physiology of the female rat during the follicular phase, some of them through the GABAA receptor. Intrabursal ALLO administration alters several processes of the ovarian morpho-physiology of the female rat, related to fertility and oocyte quality.

52 Evaluation of linseed meal on ovarian follicular development after synchronization in preovulatory small ruminants during seasonal anestrus

Abstract Seasonal estrous of small ruminants can hinder overall reproductive efficiency of holistic management strategies involving sheep and goats. The objective of this study was to quantify the effect of increased melatonin containing feed ingredients on ovarian function during seasonal anestrus. Ovarian follicle number and follicle sizes were evaluated on Spanish × Boer cross does and Rambouillet ewes amounts of lineseed meal in the treatment diet (P30DIET) or an isocoloric and isonitrogenous control diet (CON). The P30DIET contained 2.5% linseed meal which contained increased melatonin (Manchester et al. 2000). At d -18 ewes and does were stratified by age into treatment groups and the P30DIET and CON diets were supplemented (0.91 kg and 0.68 kg per animal per day for sheep and goats, respectively). Synchronization protocols were administered at d 0 for both groups and ovarian ultrasound measures were collected 48 h after the removal of the controlled internal drug release device (CIDR). Mixed model procedures of SAS were used to analyze the number of dominant follicles that were present following the synchronization protocols. The number of dominant follicles observed in the P30DIET goats was significantly greater than the CON consuming goats (P &amp;lt; 0.05). Least Squares Means estimates (LSMEANS) in the P30DIET were 1.5 ± 0.20 as compared with CON goats (0.91 ± .21). These data suggest that flushing small ruminants with greater linseed meal during the seasonal anestrus period can increase the number of dominant follicles therefore implying an improvement in reproductive efficiency in holistic management strategies of small ruminants.

Roles of sphingosine‐1‐phosphate in follicle development and oocyte maturation

AbstractSphingosine‐1‐phosphate (S1P), a lipid messenger, propagates its signals by interacting with its intracellular targets or is transported to autocrine/paracrine to activate its cell surface receptors. In the female reproductive system, the homeostasis of S1P plays an important role in ovarian follicular development. Our recent studies show that S1P emerges as a functional mediator of LH‐EGFR signaling from cumulus cells to oocytes: elevating calcium levels in cumulus cells to induce oocyte meiotic maturation, and activating Akt/mTOR cascade reaction to promote oocyte developmental competence. Thus, S1P might be applied to promote oocyte maturation in animals and humans.

Progestins for pituitary suppression during ovarian stimulation in artificial reproductive technology

Background: Progestins can suppress endogenous luteinizing hormone secretion from the pituitary gland. Progestins can be used orally and are less expensive than gonadotrophin-releasing hormone (GnRH) analogs. However, early endometrial exposure to progestin precludes fresh embryo transfer (ET), but the emergence of vitrification for oocyte cryopreservation cycles allows more opportunities for using progestins for pituitary suppression.&#x0D; Objective: To assess the mechanism of pituitary suppression by progestins, the effectiveness of progestins compared with GnRH analogs, the effect of progestins on oocyte and embryo developmental potential and euploidy status, and the cost-effectiveness of progestin-primed stimulation. &#x0D; Methods: A literature search using the keywords “multiple waves of antral ovarian follicular development, In Vitro Fertilization, Ovarian stimulation ” was performed in the PubMed database.&#x0D; Results: The duration of stimulation, gonadotrophin consumption, and oocyte yield were similar in progestins and GnRH analogs. However, progestins were associated with significantly lower gonadotrophin consumption than their analogs. Overall, live birth and clinical pregnancy rates per ET were similar to those of progestins and GnRH analogs. Studies comparing medroxyprogesterone acetate, dydrogesterone, and micronized progesterone suggest similar ovarian responses and pregnancy outcomes. The euploidy status of embryos and obstetric and neonatal outcomes from progestin-primed cycles are similar to those of embryos from conventional stimulation cycles. Despite the lower cost of progestins than GnRH analogs, the mandatory cryopreservation of all embryos followed by a deferred transfer may increase the cost per live birth with progestins compared with an artificial reproductive technology cycle culminating in a fresh ET.&#x0D; Conclusion: Progestins present an effective option for women who do not contemplate a fresh ET, e.g., fertility preservation, anticipated hyper responders, preimplantation genetic testing, oocyte donors, and double stimulation cycles.

Ovarian follicular waves in ovulation induction in assisted reproduction techniques

Background: A greater understanding of the menstrual cycle and multiple waves of antral ovarian follicular development has challenged traditional concepts of female reproductive physiology and the foundations of assisted reproductive technologies (ART). Approximately two-thirds of women develop two follicle waves throughout an interovulatory interval, and the remainder exhibit three waves of follicle development. Major and minor waves of follicle development have been observed. Major waves are those in which a dominant follicle develops; dominant follicles either regress or ovulate. In minor waves, the physiological selection of a dominant follicle is not manifested. Knowledge of the waves of antral follicular development has led to the global adoption of novel ovarian stimulation strategies in which stimulation can be initiated at various times throughout the cycle. Random-start and luteal-phase ovarian stimulation regimens have important clinical applications in women requiring urgent oocyte or embryo cryopreservation for fertility preservation before chemotherapy.&#x0D; Objective: To evaluate the role of multiple waves of the antral ovarian follicular in the menstrual cycle in ovulation induction in ART.&#x0D; Methods: A literature search using the keywords “multiple waves of antral ovarian follicular development, In Vitro Fertilization, Ovarian stimulation ” was performed in the PubMed database.&#x0D; Outcome: Random start and luteal phase of ovulation induction in ART offer the same results in fertilization and pregnancy rates as conventional early follicular phase start.&#x0D; Conclusion: The primary benefits of the random-start protocol include a patient-oriented approach to care, timely and efficient treatment, and a lower dropout rate. Women with poor ovarian reserve and those diagnosed with cancer will have a greater chance of successful assisted reproduction with the use of these strategies.

The role of the autonomic nervous system in polycystic ovary syndrome.

This article reviewed the relationship between the autonomic nervous system and the development of polycystic ovary syndrome (PCOS). PCOS is the most common reproductive endocrine disorder among women of reproductive age. Its primary characteristics include persistent anovulation, hyperandrogenism, and polycystic ovarian morphology, often accompanied by disturbances in glucose and lipid metabolism. The body's functions are regulated by the autonomic nervous system, which consists mainly of the sympathetic and parasympathetic nervous systems. The autonomic nervous system helps maintain homeostasis in the body. Research indicates that ovarian function in mammals is under autonomic neural control. The ovaries receive central nervous system information through the ovarian plexus nerves and the superior ovarian nerves. Neurotransmitters mediate neural function, with acetylcholine and norepinephrine being the predominant autonomic neurotransmitters. They influence the secretion of ovarian steroids and follicular development. In animal experiments, estrogen, androgens, and stress-induced rat models have been used to explore the relationship between PCOS and the autonomic nervous system. Results have shown that the activation of the autonomic nervous system contributes to the development of PCOS in rat. In clinical practice, assessments of autonomic nervous system function in PCOS patients have been gradually employed. These assessments include heart rate variability testing, measurement of muscle sympathetic nerve activity, skin sympathetic response testing, and post-exercise heart rate recovery evaluation. PCOS patients exhibit autonomic nervous system dysfunction, characterized by increased sympathetic nervous system activity and decreased vagal nerve activity. Abnormal metabolic indicators in PCOS women can also impact autonomic nervous system activity. Clinical studies have shown that various effective methods for managing PCOS regulate patients' autonomic nervous system activity during the treatment process. This suggests that improving autonomic nervous system activity may be an effective approach in treating PCOS.

Targeted deletion of NR2F2 and VCAM1 in theca cells impacts ovarian follicular development: insights into polycystic ovary syndrome?†.

Defining features of polycystic ovary syndrome (PCOS) include elevated expression of steroidogenic genes, theca cell androgen biosynthesis, and peripheral levels of androgens. In previous studies, we identified vascular cell adhesion molecule 1 (VCAM1) as a selective androgen target gene in specific NR2F2/SF1 (+/+) theca cells. By deleting NR2F2 and VCAM1 selectively in CYP17A1 theca cells in mice, we documented that NR2F2 and VCAM1 impact distinct and sometimes opposing theca cell functions that alter ovarian follicular development in vivo: including major changes in ovarian morphology, steroidogenesis, gene expression profiles, immunolocalization images (NR5A1, CYP11A1, NOTCH1, CYP17A1, INSL3, VCAM1, NR2F2) as well as granulosa cell functions. We propose that theca cells impact follicle integrity by regulating androgen production and action, as well as granulosa cell differentiation/luteinization in response to androgens and gonadotropins that may underlie PCOS.

Correlation between ovarian follicular development and Hippo pathway in polycystic ovary syndrome

BackgroundFor women of childbearing age, the biggest problem caused by polycystic ovary syndrome (PCOS) is infertility, which is mainly caused by anovulation, abnormal follicular development, proliferation of small antral follicles, and cystic follicles. The mechanism underlying its occurrence is not clear. The abnormal proliferation and development of follicles in PCOS patients is a complex process, which is affected by many factors. The objective of this study was to investigate the relationship between the Hippo pathway and follicular development in PCOS, and to further explore this relationship by using the YAP inhibitor verteporfin (VP).Method30 3-week-old BALB/C female rats were randomly divided into control group (n = 10), DHEA group (n = 10) and DHEA + VP group (n = 10). The morphology of ovary and the degree of follicular development were observed by HE staining, and the expression and location of AMH in ovarian follicles were observed by immunofluorescence. The ovarian reserve function index AMH, cell proliferation index PCNA and the ratio of Hippo pathway related proteins MST, LATS, YAP, P-YAP and P-YAP/YAP were detected by Western blot.ResultsAfter dividing 30 3-week-old female mice into control, dehydroepiandrosterone (DHEA; model of PCOS), and DHEA + VP groups, we found that the number of small follicles increased in the DHEA group compared to the control group. Additionally, in the DHEA group compared to the control group, anti-müllerian hormone (AMH; ovarian reserve index) increased, proliferating cell nuclear antigen (PCNA; cell proliferation index) decreased, and upstream (MST and LATS) and downstream (YAP and p-YAP) proteins in the Hippo pathway increased, though the p-YAP/YAP ratio decreased. VP ameliorated the increases in AMH, MST, LATS, YAP and p-YAP, but did not ameliorate the decrease in the p-YAP/YAP ratio.ConclusionsThis study indicates that the increased small follicles in the ovaries and changes in ovarian reserve and cell proliferation may be closely related to Hippo pathway activation. This suggests that the Hippo pathway may be an important pathway affecting the proliferation and development of follicles and the occurrence of PCOS.

Association between Vitamin D deficiency and serum anti-mullerian hormone in infertile women: a cross sectional comparative study

Background: Reproductive failure is a significant public health concern. Vitamin D influences steroidogenesis and ovarian follicular development. AMH has a crucial role in the regulation of follicular recruitment and oocyte development. Several studies have recently shown that serum AMH is affected by several factors including obesity, serum leptin and serum vitamin D. Results from studies are conflicting with some suggesting that vitamin D status is associated with ovarian reserve, whereas other studies have not found any significant correlation between vitamin D and AMH levels. Objective: To evaluate the association between vitamin D deficiencies with serum anti-mullerian hormone in infertile women. Materials and methods: The study population was the infertile women of 20-34 years of age. The women having serum anti-mullerian hormone levels ≤ 1 ng/ml were grouped as diminished ovarian reserve and those having serum anti-mullerian hormone levels &gt; 1 ng/ml were grouped as normal ovarian reserve. Serum anti-mullerian hormone and serum vitamin D levels were measured at the same day. Result: Vitamin D deficiency was defined when vitamin D levels were ≤ 20ng/ml. All infertile women with normal and diminished ovarian reserve are deficient in vitamin D. The mean serum AMH was 1.42±1.49 in vitamin D level ≤20 ng/ml and 3.14± .45 in vitamin D level &gt;20 ng/ml. Bivariate analysis was done to see that vitamin D deficiency was significantly more (calculated odds ratio 4.40) in those with diminished ovarian reserve. There was significant positive correlation between serum vitamin D level and serum anti-mullerian hormone. Conclusion: Vitamin D deficiency is associated with low serum anti-mullerian hormone in infertile women. J Bangladesh Coll Phys Surg 2024; 42: 19-24

Dynamic Expression of Follicle-Stimulating Hormone and Estrogen mRNA Receptors Associated with microRNAs 34a and -let-7c in Canine Follicles during the Estrous Cycle.

The genes encoding for estrogen receptor (ESR2) and follicle-stimulating hormone receptor (FSHR) play crucial roles in ovarian follicular development. This study aimed to determine the expression levels of miRNAs predicted against FSHR and ESR2 mRNAs in follicular cells related to their target genes during the estrous cycle in canines. Antral follicles were dissected from 72 ovaries following ovariohysterectomies. MiRNAs regulating FSHR and ESR2 genes were selected from miRNA databases, and mature miRNA and mRNA expression profiling was performed using real-time polymerase chain reaction (PCR). The best miRNA for each target gene was selected considering the quantitative PCR (qPCR) performance and target prediction probability, selecting only miRNAs with a binding p-value of 1.0, and choosing cfa-miR-34a and cfa-let-7c for FSHR and ESR2, respectively. The expression levels comparing the different phases of the estrous cycle were evaluated using ANOVA. Pearson correlations between the expression pattern of each miRNA and their target genes were performed. Each miRNA and its target genes were expressed in the granulosa cells in all estrous phases. FSHR remained low in anestrus and proestrus, increased (p < 0.05) to the highest level in estrus, and decreased (p < 0.05) in diestrus. ESR2 showed the same trend as FSHR, with the highest (p < 0.05) expression in estrus and the lowest (p < 0.05) in anestrus and proestrus. A tendency for an inverse relationship was observed between the expression of miR-34a and FSHR only in the anestrus phase, while an inverse correlation (r = -0.8) was found between miRNA-7c and ESR2 (p < 0.01). The expression profile of miR-34a and miR-let-7c and their predicted target genes of dog ovarian follicles throughout the estrous cycle observed in this study suggest a role in the transcriptional regulation of FSHR and ESR2, which is the first evidence of the involvement of these miRNAs in the canine follicular function.

Dehydroepiandrosterone modulates the PTEN/PI3K/AKT signaling pathway to alleviate 4-vinylcyclohexene diepoxide-induced premature ovarian insufficiency in rats.

Dehydroepiandrosterone (DHEA) is frequently integrated as an adjuvant in over a quarter of controlled ovarian hyperstimulation (COH) protocols, despite the ongoing debate regarding its impact. This study aimed to evaluate the efficacy and mechanism of action of DHEA on ovarian follicular development and ovarian response in rats with varying ovarian reserves. The study involved 75 rats categorized into 15 distinct groups. The ovarian tissues of rats in both the normal ovarian reserve group and the premature ovarian insufficiency (POI) group, induced by 4-vinylcyclohexene diepoxide (VCD) injection, were subjected to histomorphological and biochemical analyses following the administration of DHEA, either alone or in combination with COH. Follicle counting was performed on histological sections obtained from various tissues. Serum concentrations of AMH and the quantification of specific proteins in ovarian tissue, including PTEN, PI3K, AKT, COX-2, caspase-3, as well as assessments of total antioxidant status and total oxidant status, were conducted employing the Enzyme-Linked Immunosorbent Assay (ELISA) method. The impact of DHEA exhibited variability based on ovarian reserve. In the POI model, DHEA augmented follicular development and ovarian response to the COH protocol by upregulating the PTEN/PI3K/pAKT signaling pathway, mitigating apoptosis, inflammation, and oxidative stress, contrary to its effects in the normal ovarian reserve group. In conclusion, it has been determined that DHEA may exert beneficial effects on ovarian stimulation response by enhancing the initiation of primordial follicles and supporting antral follicle populations.

Comparison of superstimulatory protocols with different doses of eCG on ovarian response and oocyte recovery by follicular aspiration in llamas (Lama glama).

The objective of this study was to evaluate the effect of three doses of equine chorionic gonadotropin (eCG) for ovarian superstimulation on ovarian response, follicular development and cumulus-oocyte complexes (COCs) collection in llamas. For this purpose, eighteen multiparous non-lactating adult (4-7 yo) female llamas with an average body condition of 2.8 (BCS 1-5) were submitted to a follicular ablation (FA) to induce a new follicular wave emergence. Two days after FA (Day 0), synchronized llamas were randomly allocated to three treatment groups (n = 6/group) and given 500, 750 and 1000 IU of eCG (Novormon®, Syntex, Buenos Aires, Argentina) per animal respectively to induce ovarian superstimulation. Transrectal ultrasonography were performed on Days 2, 4, and 6; and ovum pick up (OPU) was performed on Day 6. Data was evaluated by one-way analysis of variance (ANOVA), repeated measures ANOVA, and 2-tailed Chi-square. The average size (mm) of follicles was greater (p≤ 0.05) in the 1000 IU group compared to the other groups. There was a greater (p≤ 0.05) number of follicles ≥ 7 mm in the 1000 IU group compared to the 500 IU group. Number of COCs collected on Day 6 and the COC recovery rate were not different among groups. In conclusion, a single dose of 1000 IU of eCG induced the best ovarian response resulting in larger and greater number of follicles at the time of OPU.

Ovarian Follicular Development Study in Jersey Crossbred Cows Reared in India

Ovarian follicular wave pattern studies provide the basis for applying reproductive intervention for improving fertility and improving the success of embryo transfer programmes in cattle. Four apparently healthy non-pregnant, pluriparous crossbred Jersey cows reared in a local farm located at Tirupur were utilized for this study. The evaluation was performed more than one plane, and all the measurable follicles (&gt;3mm) were counted and recorded every other day. Various follicular dynamics related parameters were studied such as day of wave emergence, dominant follicle, static phase of dominant follicle, regressing phase of dominant follicle, day of maximum diameter, maximum size, duration of growth, growth rate, duration of atresia, rate of atresia and duration of detection. The Ultrasonographic evaluation was performed every other day throughout an estrous cycle starting from observed estrus (Day 0) to the subsequent standing estrus. A total of 10 normal estrous cycles were monitored for follicular wave pattern, in which 8 out of 10 (80 per cent) were two wave and 2 out of 10 (20 per cent) were three wave estrous cycles. The mean length of 2-wave estrous cycle was 19.25±0.41 days and 3-wave estrous cycle was 21.50±0.50 days. It was concluded that Jersey crossbred cows frequently had 2 wave estrous cycle with pre-ovulatory follicle size 12.62±0.94mm with the growth rate of 1.13±0.12mm/day and the size of pre-ovulatory follicle in 3-wave estrous cycle was lower (10.75±1.25mm) than 2-wave estrous cycle.