Altered ovarian reserve in Ewe lambs exposed to a glyphosate-based herbicide

Glyphosate-based herbicides (GBHs) are considered endocrine disruptors that affect the female reproductive tract of rats and ewe lambs. The present study aimed to investigate the impact of neonatal exposure to a low dose of a GBH on the ovarian follicular reserve of ewe lambs and the response to a gonadotropic stimulus with porcine FSH (pFSH). To this end, ewe lambs were orally exposed to an environmentally relevant GBH dose (1 mg/kg/day) or vehicle (Control) from postnatal day (PND) 1 to PND14, and then some received pFSH (50 mg/day) between PND41 and 43. The ovaries were dissected, and follicular types and gene expression were assessed via RT-PCR. The treatments did not affect the body weight of animals, but pFSH increased ovarian weight, not observed in GBH-exposed lambs. GBH-exposed lambs showed decreased Estrogen receptor-alpha (56%), Progesterone receptor (75%), Activin receptor II (ACVRII) (85%), and Bone morphogenetic protein 15 (BMP15) (88%) mRNA levels. Control lambs treated with pFSH exhibited downregulation of Follistatin (81%), ACVRII (77%), BMP15 (93%), and FSH receptor (FSHr) (72%). GBH-exposed lambs treated with pFSH displayed reduced ACVRII (68%), BMP15 (81%), and FSHr (50%). GBH-exposed lambs also exhibited decreased Anti-Müllerian hormone expression in primordial and antral follicles (27%) and (54%) respectively) and reduced Bone morphogenetic protein 4 (31%) expression in primordial follicles. Results suggest that GBH disrupts key follicular development molecules and interferes with pFSH action in ovarian receptors, decreasing the ovarian reserve. Future studies should explore whether this decreased ovarian reserve impairs adult ovarian function and its response to superovulation stimuli.

Optimisation of hormonal treatment to improve follicular development in one-day-old mice ovaries cultured under in vitro condition

CONTEXT

Base medium containing knock-out serum replacement (KSR) has been found to support formation and maintenance of follicles in one-day-old mice ovaries, but has not been shown to properly support activation and growth of primordial follicles.

AIMS

The present study was conducted to tailor the hormonal content of base medium containing KSR to enhance development of primordial follicles in neonatal ovaries.

METHODS

One-day-old mice ovaries were initially cultured with base medium for four days, and then, different hormonal treatments were added to the culture media and the culture was proceeded for four additional days until day eight. Ovaries were collected for histological and molecular assessments on days four and eight.

KEY RESULTS

In experiment I, the main and interactive effects of FSH and testosterone were investigated and FSH promoted activation of primordial follicles and development of primary and preantral follicles, and upregulated genes of phosphoinositide 3-kinase (Pi3k ), KIT ligand (Kitl ), growth differentiation factor 9 (Gdf9 ) and follicle stimulating hormone receptor (Fshr ) (P Bmp15 ), Connexin-43 (Cx43 ) and luteinising hormone and choriogonadotropin receptor (Lhcgr ) (P P Lhcgr (P P >0.05).

CONCLUSIONS

Supplementation of culture medium containing KSR with gonadotropins, particularly hMG, could improve follicular growth and expression of factors regulating follicular development.

IMPLICATIONS

This study was a step forward in formulating an optimal medium for development of follicles in cultured one-day-old mice ovaries.

Review: Roles of follicle-stimulating hormone in preantral folliculogenesis of domestic animals: what can we learn from model species and where do we go from here?

The pituitary gonadotropin FSH is a glycoprotein critical for the development of ovarian follicles. Upon binding to its G protein-coupled membrane receptor located on the granulosa cells of ovarian follicles, FSH elicits a cascade of downstream intracellular responses to promote follicle growth, maturation and steroidogenic activity, leading to the acquisition of meiotic and developmental competence of the enclosed oocyte. The essential role of FSH for proper antral follicle development and fertility is indisputable; over the decades, increasing evidence has also pointed toward survival and growth-promoting effects elicited by FSH in earlier-stage preantral follicles, deeming these follicles FSH-responsive as opposed to the FSH-dependent antral follicles. Transgenic mouse models lacking GnRH1, Fshβ or Fshr clearly demonstrate this difference by showing that, morphologically, preantral follicles develop to the secondary stage without FSH signaling; however, exogenous expression or administration of FSH to hormone-deficient mice promotes preantral follicle development, with more pronounced effects seen in earlier stages (i.e., primary follicles). In hypophysectomized sheep, FSH administration also promotes the growth of primary-stage preantral follicles. However, in vivo studies in this area are more challenging to perform in domestic animals compared to rodents, and therefore most of the research to date has been done in vitro. Here, we present the existing evidence for a role of FSH in regulating the growth and survival of preantral follicles from data generated in rodents and domestic animals. We provide an overview of the process of folliculogenesis, FSH synthesis and cellular signaling, and the response to FSH by preantral follicles in vivo and in vitro, as well as interactions between FSH and other molecules to regulate preantral folliculogenesis. The widespread use of FSH in ovarian stimulation programs for assisted reproduction creates a real need for a better understanding of the effects of FSH beyond stimulation of antral follicle growth, and more research in this area could lead to the development of more effective fertility programs. In addition to its importance as an agricultural species, the cow provides a desirable model for humans regarding ovarian stimulation due to similar timing of folliculogenesis and follicle size, as well as similar ovarian architecture. The refinement of minimally invasive methods to allow the study of preantral folliculogenesis in live animals will be critical to understand the short- and long-term effects of FSH in ovarian folliculogenesis.

A New Bioreactor to Promote Human Follicular Growth with or without Activin A in Transgender Men

The aim of the present study was to evaluate the effect of activin A on the activation of in vitro folliculogenesis of human ovarian tissues from transgender men with or without our new compartmented chitosan hydrogel microbioreactor (“three-dimensional (3D)-structure”) enabling a three-dimensional tissue culture. Five fresh ovarian human tissues were cultured in vitro for 20 or 22 days in four groups with 100 ng/mL activin A or without activin A during the last six to eight days of culture, and within a 3D-structure or without the 3D-structure in standard conditions. Follicular density and quality were evaluated, and follicular diameters were measured. Estradiol secretion was quantified. Proliferation and apoptosis through immunostaining were also performed. The proportion of primordial follicles was significantly reduced, and the proportion of primary and secondary follicles was significantly increased in all four groups (p < 0.001). Tertiary follicles were observed in the four culture groups. Activin A supplementation did not significantly affect the follicular density, follicular quality, follicular growth, or estradiol secretion (p > 0.05). The 3D-structure increased the density of primary follicles and decreased the estradiol secretion (p < 0.001). Follicular proliferation was significantly lower in the 3D-structure group compared to the non-3D-structure group (p = 0.008). Regarding follicular apoptosis, it was significantly higher in the activin group compared to the non-activin group (p = 0.006). Activin A did not seem to play a key role in the in vitro folliculogenesis activation in our culture conditions. However, the results may indicate that the 3D-structure could be more physiological and could prevent a detrimental in vitro folliculogenesis flare-up.

Effects of follicle-stimulating hormone on fat metabolism and cognitive impairment in women during menopause

Lipid metabolism disorder is a common pathological manifestation of menopausal women, and is also an important risk factor for many diseases at this stage of life. Epidemiological studies have shown that high levels of follicle-stimulating hormone (FSH) in menopausal women are closely associated with changes in body composition, central obesity, and cognitive decline. Exogenous FSH causes growth and proliferation of adipose, whereas blockage of the FSH signaling pathway leads to decline in adipose. Mechanistically, FSH, FSH receptor (FSHR), G protein coupling, gene mutation and other pathways are involved in adipogenesis and cognitive impairment. Here, we review the critical role and potential interactions of FSH in adipogenesis and cognitive impairment in menopausal women. Further understanding of the exact mechanisms of FSH aggravating obesity and cognitive impairment may provide a new perspective for promoting healthy aging in menopausal women.

Expression of voltage-gated Ca2+ channels, Insp3Rs, and RyRs in the immature mouse ovary

Background

The postnatal mammalian ovary undergoes a series of changes to ensure the maturation of sufficient follicles to support ovulation and fecundation over the reproductive life. It is well known that intracellular [Ca2+]i signals are necessary for ovulation, fertilization, and egg activation. However, we lack detailed knowledge of the molecular identity, cellular distribution, and functional role of Ca2+ channels expressed during folliculogenesis. In the neonatal period, ovarian maturation is controlled by protein growth factors released from the oocyte and granulosa cells. Conversely, during the early infantile period, maturation becomes gonadotropin-dependent and is controlled by granulosa and theca cells. The significance of intracellular Ca2+ signaling in folliculogenesis is supported by the observation that mice lacking the expression of Ca2+/calmodulin-dependent kinase IV in granulosa cells suffer abnormal follicular development and impaired fertility.

Results

Using immunofluorescence in frozen ovarian sections and confocal microscopy, we assessed the expression of high-voltage activated Ca2+ channel alpha subunits and InsP3 and ryanodine receptors in the postnatal period from 3 to 16 days. During the neonatal stage, oocytes from primordial and primary follicles show high expression of various Ca2+-selective channels, with granulosa and stroma cells expressing significantly less. These channels are likely involved in supporting Ca2+-dependent secretion of peptide growth factors. In contrast, during the early and late infantile periods, Ca2+ channel expression in the oocyte diminishes, increasing significantly in the granulosa and particularly in immature theca cells surrounding secondary follicles.

Conclusions

The developmental switch of Ca2+ channel expression from the oocytes to the perifollicular cells likely reflects the vanishing role of the oocytes once granulosa and theca cells take control of folliculogenesis in response to gonadotropins acting on their receptors.

Phase-related differences in egg production of the migratory locust regulated by differential oosorption through microRNA-34 targeting activinβ

Outbreaks of locust plagues result from the long-term accumulation of high-density egg production. The migratory locust, Locusta migratoria, displays dramatic differences in the egg-laid number with dependence on population density, while solitarious locusts lay more eggs compared to gregarious ones. However, the regulatory mechanism for the egg-laid number difference is unclear. Herein, we confirm that oosorption plays a crucial role in the regulation of egg number through the comparison of physiological and molecular biological profiles in gregarious and solitarious locusts. We find that gregarious oocytes display a 15% higher oosorption ratio than solitarious ones. Activinβ (Actβ) is the most highly upregulated gene in the gregarious terminal oocyte (GTO) compared to solitarious terminal oocyte (STO). Meanwhile, Actβ increases sharply from the normal oocyte (N) to resorption body 1 (RB1) stage during oosorption. The knockdown of Actβ significantly reduces the oosorption ratio by 13% in gregarious locusts, resulting in an increase in the egg-laid number. Based on bioinformatic prediction and experimental verification, microRNA-34 with three isoforms can target Actβ. The microRNAs display higher expression levels in STO than those in GTO and contrasting expression patterns of Actβ from the N to RB1 transition. Overexpression of each miR-34 isoform leads to decreased Actβ levels and significantly reduces the oosorption ratio in gregarious locusts. In contrast, inhibition of the miR-34 isoforms results in increased Actβ levels and eventually elevates the oosorption ratio of solitarious locusts. Our study reports an undescribed mechanism of oosorption through miRNA targeting of a TGFβ ligand and provides new insights into the mechanism of density-dependent reproductive adaption in insects.

The continuous accumulation of high-density eggs laid by flying swarms of adults results in huge populations of flightless juveniles, which contributes to the outbreaks of locust plagues. An interesting phenomenon is that locusts have the phenotypic plasticity of reproduction. The gregarious locusts lay fewer big eggs than do solitarious phase locusts. In contrast, the solitarious phase locusts lay more small eggs compared to the gregarious locusts. We find the egg-laid number is not only regulated by the phase status of parents but also controlled by oosorption, a type of oocyte death. Further studies confirmed the phase-related ratio of oocyte death in the mother is regulated by a microRNA, which posttranscriptionally influences the expression level of a TGFβ ligand. This maternal effect on progeny size is especially critical for gregarious locusts to control the population size and maintain population fitness, and for solitarious locusts to enhance chance for gregarization and further enlargement of population size. This is the first study to reveal the molecular mechanism underlying the regulation of a microRNA-gene circuit for locust oocyte death to determine the offspring number. These findings can provide some important clues to develop potential drugs to prevent vast locust reproduction from a plague upsurge.

Activin A affects feeding by promoting the inner diameter and muscle development of the pharynx and oesophagus in zebrafish (Danio rerio) larvae

Activin A belongs to the superfamily of transforming growth factor-β and plays an important role in hormone regulation and tissue development. However, few research studies have been conducted on the effect of activin A on feeding organs in fish. In this study, the zebrafish (Danio rerio) larvae were treated with 1 ng ml^-1 activin A for 8 days continuously. The haematoxylin and eosin (H&E) staining section results revealed that the transverse inner diameter of the pharynx and oesophagus significantly increased on the third and eighth days after treatment compared with the control group (P < 0.05). On the eighth day, the cross-sectional area of the pharyngeal muscle increased by 8638 μm² compared to the control group (P < 0.05). The RNA in situ hybridization results also showed that the expression of skeletal muscle-specific genes (myog and myod) was significantly increased in pharyngeal muscle on the eighth day. Furthermore, the qRT-PCR results showed the expression of gh gene was significantly increased on the eighth day (P < 0.05). At the same time, more larvae in activin A group were able to feed larger brine shrimp (Artemia) than in the control group on the eighth day. In conclusion, activin A could affect feeding by promoting the inner diameter and muscle development of the pharynx and oesophagus in zebrafish larvae. This study is the first to report that the development of the pharynx and oesophagus can directly affect food intake in fish larvae, which provides a theoretical basis for the study of food intake of fish at an early stage.

Involvement of activin signal pathway in cyclic apoptosis of the oviductal isthmic epithelium in cows

Activin (ACV) A induces various cellular functions via activin receptor type 2 (ACVR2A/2B)-activin receptor-like kinase (ALK) 4 -Smad 2/3 pathway. Although the production of ACVA is indicated in bovine oviducts, its role on the oviduct is unclear. Oviductal isthmus needs to change its function rapidly at peri-fertilization, however, the mechanism is unknown. This study was aimed to clarify the role of ACVA in the morphological changes of oviductal isthmus in cows. First, mRNA expressions of INHBA (ACVA component) and its receptors (ALK4, ACVR2A and ACVR2B) in the isthmic tissues were examined throughout the estrous cycle. INHBA was the highest, however, ACVR2A was the lowest on the day of ovulation, suggesting reduced ACV signal transduction in the isthmus just after ovulation. Proteins of ACVRs and Smad2/3 were clearly detected in the cultured epithelial cells. It is known that ACVA regulates cellular apoptosis. Our data showed that the number of cleaved caspase-3-positive epithelial cells was largest at 2-3 days after ovulation in the isthmus. Interestingly, our study demonstrated that follistatin (ACV/TGFB/BMP inhibitor) significantly decreased the BCL2/BAX ratio in the cultured isthmic epithelial cells. To clarify which ALK pathway is involved in the regulation of BCL2/BAX ratio, the effects of SB431542 (ACV signaling (ALK4) and TGFB signaling (ALK5) inhibitor), SB525334 (ALK5 inhibitor) and LDN193189 (BMP signaling (ALK2/3) inhibitor) were investigated in the next study. The results showed that only SB431542 significantly decreased BCL2/BAX and the others had no effects. These results suggest that decreased ACVA-ACVR2A-ALK4 signal at the post-ovulation induces cyclic apoptosis of isthmic epithelial cells in bovine oviducts.

Ovarian Follicle Depletion Induced by Chemotherapy and the Investigational Stages of Potential Fertility-Protective Treatments-A Review

Ovarian follicle pool depletion, infertility, and premature menopause are all known sequelae of cancer treatment that negatively impact the quality of life of young cancer survivors. The mechanisms involved in this undesired iatrogenic ovarian damage have been intensively studied, but many of them remain unclear. Several chemotherapeutic drugs have been shown to induce direct and indirect DNA-damage and/or cellular stress, which are often followed by apoptosis and/or autophagy. Damage to the ovarian micro-vessel network induced by chemotherapeutic agents also seems to contribute to ovarian dysfunction. Another proposed mechanism behind ovarian follicle pool depletion is the overactivation of primordial follicles from the quiescent pool; however, current experimental data are inconsistent regarding these effects. There is great interest in characterizing the mechanisms involved in ovarian damage because this might lead to the identification of potentially protective substances as possible future therapeutics. Research in this field is still at an experimental stage, and further investigations are needed to develop effective and individualized treatments for clinical application. This review provides an overview of the current knowledge and the proposed hypothesis behind chemotherapy-induced ovarian damage, as well as current knowledge on possible co-treatments that might protect the ovary and the follicles from such damages.

Dose optimisation of PTEN inhibitor, bpV (HOpic), and SCF for the in-vitro activation of sheep primordial follicles

The in-vitro development of primordial follicles is critical for improving mammalian fertility and wildlife conservation. This study aimed to optimise the effective doses of bpV (HOpic) and stem cell factor (SCF) for the in-vitro activation of sheep primordial follicles. To do this, sheep ovarian cortex was treated with bpV (1.5, 15, and 150 μM) and SCF (50 and 100 ng/ml). Follicular count indicated that 15 μM bpV and 100 ng/ml SCF significantly increased normal primary follicles compared to other groups (p < 0.05). Also, a significant downregulation of P53 and PTEN, as well as the increased expression of PI3K was observed. The in-vitro maturation was more pronounced when the fragmented tissues were co-treated with selected doses of bpV and SCF. In conclusion, the combination of 15 μM bpV and 100 ng/ml SCF was the most effective treatment strategy for the activation and survival of primordial follicles in sheep ovarian fragments.

Activin promotes growth and antral cavity expansion in the dog ovarian follicle

Understanding regulators of folliculogenesis remains limited in the domestic dog (Canis familiaris), which challenges our ability to develop in vitro follicle culture systems for canid genome rescue efforts. Here, we investigated the influence of activin on dog follicle development and survival, oocyte quality, and FSH receptor expression in culture. Preantral (150 - ≤230 μm diameter), early antral (231 - ≤330 μm), and antral (>330-550 μm) stage follicles were encapsulated in a fibrin-alginate hydrogel with 0, 100, or 200 ng/ml rhActivin plus 0, 0.1, 1, or 10 μg/ml FSH for 12 or 21 d of in vitro culture. All follicle groups increased in diameter (P < 0.05) with activin acting synergistically with FSH to improve (P < 0.05) growth and antral cavity expansion (to >630 μm) in early antral and antral cohorts. This complementary effect was not linked to changes in FSHR mRNA expression (P > 0.05). Although not influencing (P > 0.05) follicle survival or transzonal projection (TZP) density in shorter term 12 d culture, activin in the presence of 1 ng/ml FSH maintained TZP density from the 12-21 d interval. Activin also increased oocyte diameter and improved nuclear integrity compared to un-supplemented controls. These results indicate that activin acts synergistically with FSH to promote growth and antral cavity expansion of the dog follicle in vitro, information useful to formulating an effective culture microenvironment for this species.

Activin A in Mammalian Physiology

Activins are dimeric glycoproteins belonging to the transforming growth factor beta superfamily and resulting from the assembly of two beta subunits, which may also be combined with alpha subunits to form inhibins. Activins were discovered in 1986 following the isolation of inhibins from porcine follicular fluid, and were characterized as ovarian hormones that stimulate follicle stimulating hormone (FSH) release by the pituitary gland. In particular, activin A was shown to be the isoform of greater physiological importance in humans. The current understanding of activin A surpasses the reproductive system and allows its classification as a hormone, a growth factor, and a cytokine. In more than 30 yr of intense research, activin A was localized in female and male reproductive organs but also in other organs and systems as diverse as the brain, liver, lung, bone, and gut. Moreover, its roles include embryonic differentiation, trophoblast invasion of the uterine wall in early pregnancy, and fetal/neonate brain protection in hypoxic conditions. It is now recognized that activin A overexpression may be either cytostatic or mitogenic, depending on the cell type, with important implications for tumor biology. Activin A also regulates bone formation and regeneration, enhances joint inflammation in rheumatoid arthritis, and triggers pathogenic mechanisms in the respiratory system. In this 30-yr review, we analyze the evidence for physiological roles of activin A and the potential use of activin agonists and antagonists as therapeutic agents.

Update on oogenesis in vitro

INTRODUCTION

Ovarian tissue is increasingly being collected from cancer patients and cryopreserved for fertility preservation. Alternately to the autologous transplantation, the development of culture systems that support oocyte development from the primordial follicle stage represent a valid strategy to restore fertility. The aim of this study is to review the most recent data regarding oogenesis in vitro and to provide an up-to-date on the contemporary knowledge of follicle growth and development in vitro.

EVIDENCE ACQUISITION

A comprehensive systematic MEDLINE search was performed since February 2018 for English-language reports by using the following terms: "ovary," "animal and human follicle," "in vitro growth and development," "ovarian tissue culture," "fertility preservation," "IVM," "oocyte." Previous published reviews and recent published original articles were preferred in order to meet our study scope.

EVIDENCE SYNTHESIS

Over time, many studies have been conducted with the aim to optimize the characteristics of ovarian tissue culture systems and to better support the three main phases: 1) activation of primordial follicles; 2) isolation and culture of growing preantral follicles; 3) removal from the follicle environment and maturation of oocyte cumulus complexes. While complete oocyte in vitro development has been achieved in mouse, with the production of live offspring, the goal of obtaining oocytes of sufficient quality to support embryo development has not been completely reached into higher mammals despite decades of effort.

CONCLUSIONS

Over the years, many improvements have been made on ovarian tissue cultures with the future purpose that patients will be provided with a greater number of developmentally competent oocytes for fertility preservation.

The Growth of Preantral Follicles and the Impact of Different Supplementations and Circumstances: A Review Study with Focus on Bovine and Human Preantral Follicles

One of the most important concerns cancer survivors face is fertility. Current treatment modalities often result in damage to the reproductive system. Different options have been proposed to preserve the fertility of affected women, and many attempts have been made to improve their chance of childbearing after therapy. Cryopreservation of ovarian tissue and follicles before the onset of cancer treatment and then either transplantation of ovarian tissue or culture of ovarian tissue and individual follicles in vitro is a commonly cited approach. Extensive research is being done to design an optimal condition for the culture of ovarian follicles. Improving follicle culture systems by understanding their actual growth needs might be a crucial step toward fertility preservation in cancer patients. This review article will try to provide a summary of the role of different factors and conditions on growth of human and bovine preantral follicles in vitro.

In-vitro regulation of primordial follicle activation: challenges for fertility preservation strategies

Ovarian tissue is increasingly being collected from cancer patients and cryopreserved for fertility preservation. While the only available option to restore fertility is autologous transplantation, this treatment is not appropriate for all patients due to the risk of reintroducing cancer cells and causing disease recurrence. Harnessing the full reproductive potential of this tissue to restore fertility requires the development of culture systems that support oocyte development from the primordial follicle stage. While this has been achieved in the mouse, the goal of obtaining oocytes of sufficient quality to support embryo development has not been reached in higher mammals despite decades of effort. In vivo, primordial follicles gradually exit the resting pool, whereas when primordial follicles are placed into culture, global activation of these follicles occurs. Therefore, the addition of a factor(s) that can regulate primordial follicle activation in vitro may be beneficial to the development of culture systems for ovarian tissue from cancer patients. Several factors have been observed to inhibit follicle activation, including anti-Müllerian hormone, stromal-derived factor 1 and members of the c-Jun-N-terminal kinase pathway. This review summarizes the findings from studies of these factors and discusses their potential integration into ovarian tissue culture strategies for fertility preservation.

Transcriptome analysis of ovine granulosa cells reveals differences between small antral follicles collected during the follicular and luteal phases

Ovarian follicular growth occurs in both the follicular and luteal phases of the estrous cycle but in very different endocrine contexts. In both phases, many small antral follicles with similar morphologic and histologic characteristics are present within the ovaries as a reserve for the terminal folliculogenesis. However, there are several gaps in our molecular knowledge of the gene expression profiles of small antral follicles in the follicular and luteal phases. The aim of the present study was to use RNA sequencing to compare and analyze the global transcriptional profile of ovine granulosa cells collected from small antral follicles (1-3 mm) either during the follicular or the luteal phase of the estrous cycle, with the hypothesis that they should be differential. We identified 663 genes whose mRNA was differentially expressed or accumulated in the granulosa cell layer of small antral follicles in the two phases. A comprehensive interpretation of these data was performed through integrative analyses (Gene Ontology, Ingenuity Pathway Analysis) and the exploitation of already available transcriptomic data on follicular growth and atresia. In particular, we observed that the contrasted endocrine context between follicular and luteal phases may have an impact on estradiol, follicle-stimulating hormone (FSH), and on the activin/inhibin signaling pathways. Furthermore, we reveal the possible initiation of early follicular atresia in small antral follicles during the follicular phase in interaction with the presence of immune cells. This study provides new insights into the gene expression profile in ovine granulosa cells, and we suggest that these molecular changes may have an implication at the time of follicle selection.

Complete in vitro oogenesis: retrospects and prospects

Precise control of mammalian oogenesis has been a traditional focus of reproductive and developmental biology research. Recently, new reports have introduced the possibility of obtaining functional gametes derived in vitro from stem cells. The potential to produce functional gametes from stem cells has exciting applications for regenerative medicine though still remains challenging. In mammalian females ovulation and fertilization is a privilege reserved for a small number of oocytes. In reality the vast majority of oocytes formed from primordial germ cells (PGCs) will undergo apoptosis, or other forms of cell death. Removal occurs during germ cell cyst breakdown and the establishment of the primordial follicle (PF) pool, during the long dormancy at the PF stage, or through follicular atresia prior to reaching the ovulatory stage. A way to solve this limitation could be to produce large numbers of oocytes, in vitro, from stem cells. However, to recapitulate mammalian oogenesis and produce fertilizable oocytes in vitro is a complex process involving several different cell types, precise follicular cell-oocyte reciprocal interactions, a variety of nutrients and combinations of cytokines, and precise growth factors and hormones depending on the developmental stage. In 2016, two papers published by Morohaku et al. and Hikabe et al. reported in vitro procedures that appear to reproduce efficiently these conditions allowing for the production, completely in a dish, of a relatively large number of oocytes that are fertilizable and capable of giving rise to viable offspring in the mouse. The present article offers a critical overview of these results as well as other previous work performed mainly in mouse attempting to reproduce oogenesis completely in vitro and considers some perspectives for the potential to adapt the methods to produce functional human oocytes.

Fertility Preservation in Cancer Patients: In Vivo and In Vitro Options

Oocyte, embryo and ovarian tissue cryopreservation are being increasingly proposed for fertility preservation among cancer patients undergoing therapy to enable them to have babies after the cancer is cured. Embryo cryopreservation is not appropriate for single girls without any sperm partner and also because oocyte retrieval is an extended procedure, it is impossible in cases requiring immediate cancer cure. Thus ovarian tissue cryopreservation has been suggested for fertility preservation especial in cancer patients. The main goal of ovarian cryopreservation is re-implanting the tissue into the body to restore fertility and the hormonal cycle. Different cryopreservation protocols have been examined and established for vitrification of biological samples. We have used Cryopin to plunge ovarian tissue into the liquid nitrogen and promising results have been observed. Ovarian tissue re-implantation after cancer cure has one problem- the possibility of recurrence of malignancy in the reimplanted tissue is high. Xenografting-implantation of the preserved tissue in another species- also has its drawbacks such as molecular signaling from the recipient. In vitro follicle culturing is a safer method to obtain mature oocytes for fertilization and the various studies that have been carried out in this area are reviewed in this paper.

Potential Use of Antiapoptotic Proteins and Noncoding RNAs for Efficient In Vitro Follicular Maturation and Ovarian Bioengineering

In vitro culture of ovarian follicles is a promising bioengineering technique for preserving fecundity in reproductive-aged female by providing fertilizable oocytes. Successful clinical application should be preceded by developing the protocols that can efficiently overcome follicular cell apoptosis since the apoptosis is a critical phenomenon in in vivo folliculogenesis and in in vitro follicular maturation. Numerous prosurvival and antiapoptotic molecules, including follicular developmental regulators, have been reported to be involved in the intraovarian apoptosis. The authors searched literature and analyzed the current knowledge of these proteins and noncoding RNAs, and their antiapoptotic roles in the dynamics of follicular development in vivo and in vitro. Two-dimensional (2D) culture method has widely been used, however, with recent emergence of various biomaterials, three-dimensional (3D) culture is also considered a proper environment for maintenance of solid structure of ovarian follicles. The identification of candidate paracrine and endocrine intracellular effectors that are responsible for the coordination occurring between oocyte, granulosa, and theca cells during follicular development was explored in this review, to assess the possibility of their use as antiapoptotic factors in establishing more efficacious 2D or 3D in vitro follicular microenvironment. The retrieved information will provide an inventory and the insight for defining more sophisticated culture conditions that are essential for functional artificial ovarian bioengineering.

Intra-cellular mechanism of Anti-Müllerian hormone (AMH) in regulation of follicular development

Anti-Müllerian hormone (AMH) is a member of the transforming growth factor-β superfamily and plays a crucial role in testicular and ovarian functions. In clinical practice, AMH is used as a diagnostic and/or prognostic marker in women in association with ovulation induction and in various pathophysiological conditions. Despite widespread clinical use of AMH, our mechanistic understanding of AMH actions in regulating follicular development is limited. Using a mouse model, we in this study report that in vivo AMH treatment while stalls follicular development and inhibits ovulation, also prevents follicular atresia. We further show that these AMH actions are mediated through induction of two miRNAs, miR-181a and miR-181b, which regulate various aspects of FSH signaling and follicular growth, ultimately affecting downstream gene expression and folliculogenesis. We also report that in this mouse model AMH pre-treatment prior to superovulation improves oocyte yield. These studies, therefore, offer new mechanistic insight into AMH actions in folliculogenesis and point toward potential utilization of AMH as a therapeutic agent.

The effect of FSH and activin A on Akt and MAPK1/3 phosphorylation in cultured bovine ovarian cortical strips

Background

rhFSH and rhActA have been used in mammalian ovarian follicle culture systems for activation of follicular growth in vitro and suggested to be responsible for primordial follicle survival through MAPK and Akt pathways. The aim of our study was to determine the effects of rhFSH and rhActA on Akt, pAkt, MAPK1/3 and pMAPK1/3 protein levels in bovine ovarian cortical strips cultured in vitro.

Methods

Ovarian cortical strips from heifers were cultured in the presence of rhFSH (50 ng/mL), rhActA (100 ng/mL) or combination of these factors for 6 days. The strips were embedded in paraffin for histological observations and homogenized for western blot to determine Akt, pAkt, MAPK1/3 and pMAPK1/3 protein levels after the culture. Determination of primordial, primary and secondary follicle proportions at the end of culture as well as comparison of healthy follicle for each developmental stage after the culture was performed to quantify follicle survival and activation.

Results

pAkt protein levels were significantly lower in rhFSH + rhActA group among the other groups, whereas pMAPK1/3 levels were not significantly changed. Follicular activation and survival was measured to be significantly lower in rhFSH + rhActA group. Percentage of healthy primordial follicles was higher in control group whereas healthy secondary follicle proportion was higher in both rhActA and rhFSH groups. rhActA alone had a better impact on follicular activation, since the percentage of the secondary follicles was significantly higher than other treatment groups.

Conclusions

The use of rhActA and rhFSH alone or in the combined form results in differential levels of Akt and MAPK proteins. Both rhActA and rhFSH alone has a remarkable contribution in survival and activation of the follicles in accordance with higher levels of these proteins. Thus, the manipulation of Akt and MAPK pathways with appropriate activators might contribute to proper activation and development of ovarian follicles in vitro.

Activin Decoy Receptor ActRIIB:Fc Lowers FSH and Therapeutically Restores Oocyte Yield, Prevents Oocyte Chromosome Misalignments and Spindle Aberrations, and Increases Fertility in Midlife Female SAMP8 Mice

Women of advanced maternal age (AMA) (age ≥ 35) have increased rates of infertility, miscarriages, and trisomic pregnancies. Collectively these conditions are called "egg infertility." A root cause of egg infertility is increased rates of oocyte aneuploidy with age. AMA women often have elevated endogenous FSH. Female senescence-accelerated mouse-prone-8 (SAMP8) has increased rates of oocyte spindle aberrations, diminished fertility, and rising endogenous FSH with age. We hypothesize that elevated FSH during the oocyte's FSH-responsive growth period is a cause of abnormalities in the meiotic spindle. We report that eggs from SAMP8 mice treated with equine chorionic gonadotropin (eCG) for the period of oocyte growth have increased chromosome and spindle misalignments. Activin is a molecule that raises FSH, and ActRIIB:Fc is an activin decoy receptor that binds and sequesters activin. We report that ActRIIB:Fc treatment of midlife SAMP8 mice for the duration of oocyte growth lowers FSH, prevents egg chromosome and spindle misalignments, and increases litter sizes. AMA patients can also have poor responsiveness to FSH stimulation. We report that although eCG lowers yields of viable oocytes, ActRIIB:Fc increases yields of viable oocytes. ActRIIB:Fc and eCG cotreatment markedly reduces yields of viable oocytes. These data are consistent with the hypothesis that elevated FSH contributes to egg aneuploidy, declining fertility, and poor ovarian response and that ActRIIB:Fc can prevent egg aneuploidy, increase fertility, and improve ovarian response. Future studies will continue to examine whether ActRIIB:Fc works via FSH and/or other pathways and whether ActRIIB:Fc can prevent aneuploidy, increase fertility, and improve stimulation responsiveness in AMA women.

Cooperative Effects of FOXL2 with the Members of TGF-β Superfamily on FSH Receptor mRNA Expression and Granulosa Cell Proliferation from Hen Prehierarchical Follicles

Forkhead box L2 (FOXL2) is a member of the forkhead nuclear factor 3 gene family and plays an essential role in ovarian growth and maturation in mammals. However, its potential effects and regulative mechanism in development of chicken ovarian prehierarchical follicles remain unexplored. In this study, the cooperative effects of FOXL2 with activin A, growth differentiation factor-9 (GDF9) and follistatin, three members of the transforming growth factor beta (TGF-β) superfamily that were previously suggested to exert a critical role in follicle development was investigated. We demonstrated herein, using in-situ hybridization, Northern blot and immunohistochemical analyses of oocytes and granulosa cells in various sizes of prehierarchical follicles that both FOXL2 transcripts and FOXL2 proteins are predominantly expressed in a highly similar expression pattern to that of GDF9 gene. In addition, the FOXL2 transcript was found at lower levels in theca cells in the absence of GDF9. Furthermore, culture of granulosa cells (GCs) from the prehierarchical follicles (6–8 mm) in conditioned medium revealed that in the pcDNA3.0-FOXL2 transfected GCs, there was a more dramatic increase in FSHR mRNA expression after treatment with activin A (10 ng/ml) or GDF9 (100 ng/ml) for 24 h which caused a stimulatory effect on the GC proliferation. In contrast, a significant decrease of FSHR mRNA was detected after treatment with follistatin (50 ng/ml) and resulted in an inhibitory effect on the cell proliferation. The results of this suggested that FOXL2 plays a bidirectional modulating role involved in the intracellular FSHR transcription and GC proliferation via an autocrine regulatory mechanism in a positive or negative manner through cooperation with activin A and/or GDF9, and follistatin in the hen follicle development. This cooperative action may be mediated by the examined Smad signals and simultaneously implicated in modulation of the StAR, CCND2, and CYP11A1 expression.

Effects of anti-Müllerian hormone and follicle stimulating hormone levels on in vitro fertilization pregnancy rate

OBJECTIVES

To analyze the relationship between in vitro fertilization (IVF) pregnancy rate and basal serum hormone levels before patients begin an IVF course.

MATERIALS AND METHODS

In this retrospective study, we analyzed patients with anti-Müllerian hormone (AMH) data and IVF data from January 2009 to October 2012. Pregnancy rates were calculated by AMH and follicle stimulating hormone quartiles and analyzed using the independent samples t test. Furthermore, patients were divided into three groups by age. The Chi-square test was used to assess the association between the parameters and IVF pregnancy rates.

RESULTS

From the 910 IVF treatment courses, 377 (41.4%) clinical pregnancies resulted. The pregnant and nonpregnant groups differed significantly in age and FSH and AMH levels. The pregnancy rate was 53.3% for patients aged <32 years and 22.1% for patients aged >38 years. The pregnancy rate was 53.4% for patients with FSH levels <5.6 mIU/mL and 25.8% for patients with FSH levels >8.9 mIU/mL. The pregnancy rate was 56.8% for patients with AMH levels >4.0 ng/mL and 20.0% for patients with AMH levels <1.1 ng/mL. Furthermore, among patients aged <40 years, AMH and FSH were significantly associated with pregnancy rate. Higher pregnancy rates were found among the groups with higher AMH levels than in groups with lower AMH levels.

CONCLUSION

For patients aged <40 years, basal serum AMH level and FSH level affected the IVF pregnancy rate, and patients with higher AMH levels had better pregnancy rates.

Molecular mechanisms of enhancing porcine granulosa cell proliferation and function by treatment in vitro with anti-inhibin alpha subunit antibody

BACKGROUND

This study was conducted to clarify the effect of the inhibiting action of inhibin on porcine granulosa cell proliferation and function, and to investigate the underlying intracellular regulatory molecular mechanisms.

METHODS

Porcine granulosa cells were cultured in vitro, and were treated with an anti-inhibin alpha subunit antibody, with or without co-treatment of follicle-stimulating hormone (FSH) in the culture medium.

RESULTS

Treatment with anti-inhibin alpha subunit antibody led to a significant increase in estradiol (E2) secretion and cell proliferation. Anti-inhibin alpha subunit antibody worked synergistically with FSH at low concentrations (25 microg/mL) to stimulate E2 secretion, but attenuated FSH action at high concentrations (50 microg/mL). Immunoneutralization of inhibin bioactivity increased FOXL2, Smad3, and PKA phosphorylation, and mRNA expression of the transcription factors CEBP and c-FOS. The expression of genes encoding gonadotropin receptors, FSHR and LHR, and of those involved in steroidogenesis, as well as IGFs and IGFBPs, the cell cycle progression factors cyclinD1 and cyclinD2, and the anti-apoptosis and anti-atresia factors Bcl2, TIMP, and ADAMTS were upregulated following anti-inhibin alpha-subunit treatment. Treatment with anti-inhibin alpha subunit down regulated expression of the pro-apoptotic gene encoding caspase3. Although expression of the pro-angiogenesis genes FN1, FGF2, and VEGF was upregulated, expression of the angiogenesis-inhibiting factor THBS1 was downregulated following anti-inhibin alpha subunit treatment.

CONCLUSIONS

These results suggest that immunoneutralization of inhibin bioactivity, through augmentation of the activin and gonadotropin receptor signaling pathways and regulation of gene expression, permits the development of healthy and viable granulosa cells. These molecular mechanisms help to explain the enhanced ovarian follicular development observed following inhibin immunization in animal models.

Differential gene expression in ovaries of Qira black sheep and Hetian sheep using RNA-Seq technique

The Qira black sheep and the Hetian sheep are two local breeds in the Northwest of China, which are characterized by high-fecundity and low-fecundity breed respectively. The elucidation of mRNA expression profiles in the ovaries among different sheep breeds representing fecundity extremes will helpful for identification and utilization of major prolificacy genes in sheep. In the present study, we performed RNA-seq technology to compare the difference in ovarian mRNA expression profiles between Qira black sheep and Hetian sheep. From the Qira black sheep and the Hetian sheep libraries, we obtained a total of 11,747,582 and 11,879,968 sequencing reads, respectively. After aligning to the reference sequences, the two libraries included 16,763 and 16,814 genes respectively. A total of 1,252 genes were significantly differentially expressed at Hetian sheep compared with Qira black sheep. Eight differentially expressed genes were randomly selected for validation by real-time RT-PCR. This study provides a basic data for future research of the sheep reproduction.

Slow-freezing versus vitrification for human ovarian tissue cryopreservation

PURPOSE

Ovarian tissue can be cryopreserved prior to chemotherapy using either the slow-freezing or the vitrification method; however, the data on the equality of the procedures are still conflicting. In this study, a comparison of the cryo-damage of human ovarian tissue induced by either vitrification or slow-freezing was performed.

METHODS

Ovarian tissue from 23 pre-menopausal patients was cryopreserved with either slow-freezing or vitrification. After thawing/warming, the tissue was histologically and immunohistochemically analyzed and cultured in vitro. During tissue culture the estradiol release was assessed.

RESULTS

No significant difference was found in the proportion of high-quality follicles after thawing/warming in the slow-freezing and vitrification group, respectively (72.7 versus 66.7 %, p = 0.733). Estradiol secretion by the ovarian tissue was similar between groups during 18 days in vitro culture (area-under-the-curve 5,411 versus 13,102, p = 0.11). Addition of Sphingosine-1-Phosphate or Activin A to the culture medium did not alter estradiol release in both groups. The proportion of Activated Caspase-3 or 'Proliferating-Cell-Nuclear-Antigen' positive follicles at the end of the culture period was similar between slow-freezing and vitrification.

CONCLUSION(S)

Slow-freezing and vitrification result in similar morphological integrity after cryopreservation, a similar estradiol release in culture, and similar rates of follicular proliferation and apoptosis after culture.

Recombinant activin A enhances the growth and survival of isolated preantral follicles cultured three-dimensionally in extracellular basement matrix protein (matrigel) under serum-free conditions

Development of in vitro technologies that will allow the culture of early stage follicles before antral stage is an essential part of research in reproductive biology in order to understand the ovarian folliculogenesis better. Current evidence suggests that oocyte and somatic cells-derived growth factors interacting with each other and extracellular matrix proteins at paracrine level are involved in this early, gonadotrophin-independent phase of follicle growth. Basement membrane matrix protein (Matrigel™) is a soluble gel rich in extracellular matrix proteins and growth factors. Activin A promotes preantral follicle growth in vivo by inducing the proliferation of granulosa cells and by upregulating the expression of FSH receptor and aromatase enzyme. We hypothesized that activin A and matrigel may provide a better in vitro environment for early stage preantral follicles. Preantral follicles isolated from 14-21 day old BALB/c mice were cultured in matrigel ± activin A for four days. The growth (119.4% versus 45.4%, p < 0.05; respectively) and survival rates (76.3% versus 43.7%, p < 0.05; respectively) of the follicles treated with activin A were significantly higher compared to those without activin A. These results suggest that Activin A and matrigel provide a better in vitro milieu for the growth of isolated ovarian follicles.

The effects of fibroblast co-culture and activin A on in vitro growth of mouse preantral follicles

BACKGROUND

This study was conducted to evaluate fibroblast co-culture and Activin A on in vitro maturation and fertilization of mouse preantral follicles.

METHODS

The ovaries from 12-14-day-old mice were dissected, and 120-150 μm preantral follicles were cultured individually in α-MEM as based medium for 12 days. A total number of 456 follicles were cultured in four conditions: (i) base medium as control group (n = 113), (ii) base medium supplemented with 30 ng/ml Activin A (n = 115), (iii) base medium co-cultured with mouse embryonic fibroblast (n = 113), and (iv) base medium supplemented with 30 ng/ml Activin A and co-cultured with fibroblast (n = 115). Rate of growth, survivability, antrum formation, ovulation, embryonic development and steroid production were evaluated. Analysis of Variance and Duncan test were applied for analyzing.

RESULTS

Both co-culture and co-culture + Activin A groups showed significant difference (P<0.05) in growth (on days 4, 6, and 8 of culture period) and survival rates. However, there was no significant difference in antrum formation, ovulation rate, and embryonic development of ovulated oocytes. There were significant differences (P<0.05) in the estradiol production on days 8, 10, and 12 between co-culture + Activin A and the control group. Progesterone production also was significant (P<0.05) in co-culture + Activin A group on days 6, 8, 10, and 12 compared to control group.

CONCLUSION

Fibroblast co-culture and Activin A promoted growth and survivability of preantral follicles. However, simultaneous use of them was more efficient.

Activin-A promotes the development of goat isolated secondary follicles in vitro

The role of activin-A in follicular development and on the mRNA expression levels of different genes in goat secondary follicles was evaluated. Goat secondary follicles (≥ 150 μm) were cultured for 18 days under control conditions or with the addition of either 50 or 100 ng/ml activin-A (Experiment 1). The mRNA levels for the genes that code for activin-A, ActR-IA, ActR-IB, ActR-IIA, ActR-IIB, follicle stimulating hormone receptor (FSH-R) and P450 aromatase were measured in each condition (Experiment 2). We observed that after 6 days of culture, the antrum formation rate was higher in cultures with added activin-A than in the cultured control (P < 0.05). The addition of 50 ng/ml activin-A increased the follicular growth rate in the final third of the culture (days 12-18), resulting in a higher percentage of meiosis resumption (P < 0.05). On day 6, the addition of activin-A (50 ng/ml) increased the levels of ActR-IA mRNA compared with the cultured control (P < 0.05). After 18 days, the addition of 50 ng/ml activin-A significantly increased the levels of its own mRNA compared with the non-cultured control. Moreover, this treatment reduced the mRNA levels of P450 aromatase in comparison with the cultured control (P < 0.05). Higher levels of P450 aromatase mRNA were found for both activin-A treatments compared with the non-cultured control (P < 0.05). No difference in estradiol levels was detected among any of the tested treatments. In conclusion, the addition of activin-A to culture medium stimulated early antrum formation as well as an increase in the daily follicular growth rate and the percentage of meiosis resumption.