Unveiling the Ovarian Cell Characteristics and Molecular Mechanism of Prolificacy in Goats via Single-Nucleus Transcriptomics Data Analysis

Increases in litter size, which are influenced by ovulation, are responsible for between 74% and 96% of the economic value of genetic progress, which influences selection. For the selection and breeding of highly prolific goats, genetic mechanisms underlying variations in litter size should be elucidated. Here, we used single-nucleus RNA sequencing to analyze 44,605 single nuclei from the ovaries of polytocous and monotocous goats during the follicular phase. Utilizing known reference marker genes, we identified 10 ovarian cell types characterized by distinct gene expression profiles, transcription factor networks, and reciprocal interaction signatures. An in-depth analysis of the granulosa cells revealed three subtypes exhibiting distinct gene expression patterns and dynamic regulatory mechanisms. Further investigation of cell-type-specific prolificacy-associated transcriptional changes elucidated that "downregulation of apoptosis", "increased anabolism", and "upstream responsiveness to hormonal stimulation" are associated with prolificacy. This study provides a comprehensive understanding of the cell-type-specific mechanisms and regulatory networks in the goat ovary, providing insights into the molecular mechanisms underlying goat prolificacy. These findings establish a vital foundation for furthering understanding of the molecular mechanisms governing folliculogenesis and for improving the litter size in goats via molecular design breeding.

Random start ovarian stimulation before gonadotoxic therapies in women with cancer: a systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to quantify the effect of random start ovarian stimulation (RSOS) compared with conventional start ovarian stimulation (CSOS) in cancer patients before gonadotoxic treatment. The final analytical cohort encompassed 688 RSOS and 1076 CSOS cycles of cancer patients before gonadotoxic treatment. Eleven studies were identified by database searches of MEDLINE, Cochrane Library and cited references. The primary outcomes of interest were the number of oocytes and mature oocytes collected, the number of embryos cryopreserved and the metaphase II (MII)-antral follicle count (AFC) ratio. The studies were rated from medium to high quality (from 6 to 9) according to the Newcastle-Ottawa Quality Assessment Scale. The two protocols resulted in similar numbers of oocytes collected, MII oocytes, embryos available for cryopreservation and comparable MII-AFC and fertilization rates. The duration of ovarian stimulation was longer (standardized mean difference [SMD] 0.35, 95% CI 0.09 to 0.61; P = 0.009) and gonadotrophin consumption was higher (SMD 0.23, 95% CI 0.06 to 0.40; P = 0.009) in RSOS compared with CSOS. This systematic review and meta-analysis show that the duration of stimulation is longer, and the total gonadotrophin consumption is higher in cancer patients undergoing RSOS compared with those undergoing CSOS, with no significant effect on mature oocyte yield.

Follicular steroidogenesis in random start protocols for oocyte cryopreservation

PURPOSE

Random start protocols are commonly used for oocyte cryopreservation in women with cancer. However, albeit generally reassuring, available evidence is still insufficient to rule out a sub-optimal cycle outcome. This study aimed to compare follicular steroidogenesis between women initiating the random start protocol in the luteal phase and those initiating in the follicular phase.

METHODS

Consecutive women with cancer scheduled for oocyte cryostorage were prospectively recruited. We excluded those requiring a concomitant letrozole assumption. All women received a standardized protocol with recombinant FSH and GnRH antagonists. At the time of oocyte retrieval, follicular fluids were pooled, and a sample was collected and frozen at -80 °C. All samples were assayed concomitantly after thawing by liquid chromatography-tandem mass spectrometry. The concentration of 15 different steroid hormones was determined.

RESULTS

Seventy-one women were recruited. Thirty-three initiated the ovarian stimulation in the luteal phase, while the remaining 38 initiated in the follicular phase. Baseline characteristics were generally similar. Cycle outcome did also not differ; the median (interquartile range) number of frozen mature oocytes was 9 (5-14) and 10 (5-21), respectively (p = 0.42). None of the 15 tested steroid hormones differed.

CONCLUSIONS

The endocrine microenvironment surrounding oocytes is not markedly influenced by the phase of the menstrual cycle at the initiation of ovarian stimulation. This result further supports the validity of random start protocols.

Bovine models for human ovarian diseases

During early embryonic development, late fetal growth, puberty, adult reproductive years, and advanced aging, bovine and human ovaries closely share molecular pathways and hormonal signaling mechanisms. Other similarities between these species include the size of ovaries, length of gestation, ovarian follicular and luteal dynamics, and pathophysiology of ovarian diseases. As an economically important agriculture species, cattle are a foundational species in fertility research with decades of groundwork using physiologic, genetic, and therapeutic experimental techniques. Many technologies used in modern reproductive medicine, such as ovulation induction using hormonal therapy, were first used in cows before human trials. Human ovarian diseases with naturally occurring bovine correlates include premature ovary insufficiency (POI), polycystic ovarian syndrome (PCOS), and sex-cord stromal tumors (SCSTs). This article presents an overview of bovine ovary research related to causes of infertility, ovarian diseases, diagnostics, and therapeutics, emphasizing where the bovine model can offer advantages over other lab animals for translational applications.

Comparison of Oocyte and Embryo Quality Between Random Start and Controlled Ovarian Stimulation Cycles in Cancer Patients Undergoing Fertility Preservation

Conventional assisted reproductive technology (ART) cycles may delay cancer treatment and compromise survival, and also increase patients' psychological burden as a result of delayed chemotherapy. The aim of this study was to compare the success rates of random start and conventional start GnRH antagonist protocols in terms of oocyte and embryo outputs in cancer patients. Data of 111 patients with a newly diagnosed cancer who underwent ART for fertility preservation at a university-based infertility clinic between January 2010 and September 2019 were reviewed. The study group underwent random start controlled ovarian hyperstimulation (RS-COH) and the control group underwent conventional start COH (CS-COH). The main outcome measures were the number of total oocytes, MII oocytes, and embryo yield. A total of 46 patients (41.5%) underwent RS-COH and 65 (58.5%) underwent CS-COH. Baseline characteristics were similar between the groups. The most common cancer type in both groups was breast cancer (60.9% vs. 52.3%, respectively). The median duration of stimulation was significantly longer in RS-COH than in CS-COH (12 vs. 10 days; P = 0.005). The median number of MII oocytes was significantly higher in RS-COH than in CS-COH (7 vs. 5 oocytes, respectively; P = 0.020). The MII/AFC ratio was significantly higher in the RS-COH group compared to the CS-COH group (74% and 57% respectively; p = 0.02). In the linear regression analyses, RS-COH protocol did not have a significant impact on MII/AFC (standardized ß coefficient - 0.514; P = 0.289 {adjusted R² for the model = 0.779}), oocyte yield (standardized ß coefficient - 0.070; P = 0.829 {adjusted R² for the model = 0.840}), and MII rate (standardized ß coefficient - 0.504; P = 0.596 {adjusted R² for the model = 0.271}). In conclusion, RS-COH protocol is as effective as CS-COH protocols for fertility preservation in cancer patients.

Hormone-Like Effects of 4-Vinylcyclohexene Diepoxide on Follicular Development

Background

4-vinylcyclohexene diepoxide (VCD) has long been considered a hazardous occupational chemical that promotes ovarian failure. However, VCD is also used as a research compound to chemically induce animal models of premature ovarian insufficiency (POI), and in related work we unexpectedly found that VCD apparently exhibits both dose- and duration-dependent opposing, hormone-like effects on the maintenance of the primordial follicle pool, follicle development, and ovulation induction.

Results

We conducted experiments with cultured murine ovaries and performed transplantation experiments using postnatal day (PD) 2 and PD12 mice and found that low-dose, short-term exposure to VCD (VCD^low) actually protects the primordial/primary follicle pool and improves the functional ovarian reserve (FOR) by disrupting follicular atresia. VCD^low inhibits follicular apoptosis and regulates the Pten-PI3K-Foxo3a pathway. Short-term VCD exposure in vivo (80 mg/kg, 5 days) significantly increases the number of superovulated metaphase II oocytes, preovulatory follicles, and corpus luteum in middle-aged mice with diminished ovarian reserve (DOR). We demonstrate that low-dose but not high-dose VCD promotes aromatase levels in granulosa cells (GCs), thereby enhancing the levels of estradiol secretion.

Conclusion

Our study illustrates a previously unappreciated, hormone-like action for the occupational “ovotoxin” molecule VCD and strongly suggests that VCD^low should be explored for its potential utility for treating human ovarian follicular development disorders, including subfertility in perimenopausal women.

Single-cell reconstruction of follicular remodeling in the human adult ovary

The ovary is perhaps the most dynamic organ in the human body, only rivaled by the uterus. The molecular mechanisms that regulate follicular growth and regression, ensuring ovarian tissue homeostasis, remain elusive. We have performed single-cell RNA-sequencing using human adult ovaries to provide a map of the molecular signature of growing and regressing follicular populations. We have identified different types of granulosa and theca cells and detected local production of components of the complement system by (atretic) theca cells and stromal cells. We also have detected a mixture of adaptive and innate immune cells, as well as several types of endothelial and smooth muscle cells to aid the remodeling process. Our results highlight the relevance of mapping whole adult organs at the single-cell level and reflect ongoing efforts to map the human body. The association between complement system and follicular remodeling may provide key insights in reproductive biology and (in)fertility.

Outcomes of random start versus clomiphene citrate and gonadotropin cycles in occult premature ovarian insufficiency patients, refusing oocyte donation: a retrospective cohort study

The aim of this study is to present the clinical outcomes of a random start, a spontaneous folliculogenesis protocol versus Clomiphene Citrate and Gonadotropin treatment in women with occult premature ovarian insufficiency. Women underwent treatment between 1 February 2009, and 30 May 2016. 41 women were treated with the random start protocol while 48 cases received ovarian stimulation with clomiphene and gonadotropins. All included cases met the criteria of 4 months of oligo-ovulation, follicular-stimulating hormone levels over 30 IU/L and anti-Mullerian hormone levels below 0.30 ng/mL. The random start protocol involved following the subjects for up to 6 months until spontaneous folliculogenesis occurred. The mean number of oocytes collected, mature oocytes, fertilized oocytes, and grade II embryos were significantly higher in the random start protocol (p < .05). The doses of gonadotropin administration and hCG were significantly lower in the random start protocol (p < .05). The clinical pregnancy and live birth rates were significantly higher in the random start protocol (p < .05). Likely stimulation is of little benefit in women with occult premature ovarian insufficiency. Observation while waiting for spontaneous folliculogenesis results in better outcomes, and less oocyte collections.

Ovarian manipulation in ART: going beyond physiological standards to provide best clinical outcomes

Current knowledge on ovarian physiology has challenged the traditional concept of folliculogenesis, creating the basis for novel ovarian stimulation protocols in assisted reproduction technology. The purpose of this review was to evaluate the efficacy of novel clinical interventions that could aid clinicians in individualizing their protocols to patients' characteristics and personal situations. We conducted a literature review of the available evidence on new approaches for ovarian stimulation from both retrospective and prospective studies in the PubMed database. Here, we present some of the most important interventions, including follicle growth in the gonadotropin-independent and dependent stage, manipulation of estradiol production throughout ovarian stimulation, control of mid-cycle gonadotropin surges, and luteal phase support after different stimulation protocols and trigger agents. The latest research on IVF has moved physicians away from the classical physiology, allowing the development of new strategies to decouple organ functions from the female reproductive system and challenging the traditional concept of IVF.

Random-start ovarian stimulation in women desiring elective cryopreservation of oocytes

The current study investigates the utility of random-start ovarian stimulation in women desiring elective oocyte cryopreservation. Women in the study cohort underwent random-start ovarian stimulation, and were subdivided based on the phase of the menstrual cycle that ovarian stimulation began, i.e. early follicular, late follicular or luteal phase. Women undergoing conventional cycle day (CD) 2/3 ovarian stimulation start were controls. A total of 1302 women were included - 859 (66.0%) conventional CD 2/3, 342 (26.3%) early follicular, 42 (3.2%) late follicular and 59 (4.5%) luteal ovarian stimulation starts. There was no difference in the demographics or baseline ovarian stimulation characteristics. The duration of ovarian stimulation (11 versus 9 days; P < 0.001) and total dosage of gonadotrophins administered (4095.5 versus 3155 IU; P < 0.001) was higher in the random-start group. The number of total and MII oocytes in the control and random-start groups was similar. A non-significant trend towards increased cycle cancellation was noted in the late follicular start group (7.1%). Study findings indicate the number of total and MII oocytes derived from random-start protocols initiated during any phase of the menstrual cycle is similar to conventional CD 2/3 ovarian stimulation start protocols in women desiring elective oocyte cryopreservation.

The influence of in vitro fertilization and embryo culture on the embryo epigenetic constituents and the possible consequences in the bovine model

Medically assisted reproductive technologies, such as in vitro embryo production, are increasingly being used to palliate infertility. Eggs are produced following a hormonal regimen that stimulates the ovaries to produce a large number of oocytes. Collected oocytes are then fertilized in vitro and allowed to develop in vitro until they are either frozen or transferred to mothers. There are controversial reports on the adverse impacts of these technologies on early embryos and their potential long-term effects. Using newly developed technological platforms that enable global gene expression and global DNA methylation profiling, we evaluated gene perturbations caused by such artificial procedures. We know that cells in the early embryo produce all cells in the body and are able to respond to their in vitro environment. However, it is not known whether gene perturbations are part of a normal response to the environment or are due to distress and will have long-term impacts. While the mouse is an established genetic model used for quality control of culture media in clinics, the bovine is a large mono-ovulating mammal with similar embryonic kinetics as humans during the studied developmental window. These model systems are critical to understand the effects of assisted reproduction without the confounding impact of infertility and without the limitations imposed by the scarcity of donated human samples and ethical issues. The data presented in this review come mostly from our own experimentation, publications, and collaborations. Together they demonstrate that the in vitro environment has a significant impact on embryos at the transcriptomic level and at the DNA methylation level.

Toward precision medicine for preserving fertility in cancer patients: existing and emerging fertility preservation options for women

As the number of young cancer survivors increases, quality of life after cancer treatment is becoming an ever more important consideration. According to a report from the American Cancer Society, approximately 810,170 women were diagnosed with cancer in 2015 in the United States. Among female cancer survivors, 1 in 250 are of reproductive age. Anticancer therapies can result in infertility or sterility and can have long-term negative effects on bone health, cardiovascular health as a result of reproductive endocrine function. Fertility preservation has been identified by many young patients diagnosed with cancer as second only to survival in terms of importance. The development of fertility preservation technologies aims to help patients diagnosed with cancer to preserve or protect their fertility prior to exposure to chemo- or radiation therapy, thus improving their chances of having a family and enhancing their quality of life as a cancer survivor. Currently, sperm, egg, and embryo banking are standard of care for preserving fertility for reproductive-age cancer patients; ovarian tissue cryopreservation is still considered experimental. Adoption and surrogate may also need to be considered. All patients should receive information about the fertility risks associated with their cancer treatment and the fertility preservation options available in a timely manner, whether or not they decide to ultimately pursue fertility preservation. Because of the ever expanding number of options for treating cancer and preserving fertility, there is now an opportunity to take a precision medicine approach to informing patients about the fertility risks associated with their cancer treatment and the fertility preservation options that are available to them.

Live birth following early follicular phase oocyte collection and vitrified-warmed embryo transfer 8 days later

A 30-year-old woman with premature ovarian insufficiency had two follicles measuring 17 mm and 14 mm on day 3 of her menstrual cycle. Serum oestradiol concentration was 210 pg/ml. Recombinant human chorionic gonadotrophin was given and 5 mg/day letrozole started orally. One metaphase II oocyte was collected 36 h later. A 4-cell embryo was vitrified on the second day after fertilization. Letrozole was stopped on cycle day 8 due to absence of any other visible antral follicles. Oestradiol valerate 6 mg/day was started and the endometrium was 9.2 mm on cycle day 11. The embryo was warmed and transferred on cycle day 13, the 8th day after oocyte retrieval. Luteal phase support with progesterone, oestradiol and low molecular weight heparin was started on the day of transfer and continued until the 10th gestational week. A healthy girl weighing 3200 g was born at term. Early follicular phase oocyte collection did not result in early opening of the implantation window. Apparently secretory transformation was not started until luteal phase support, enabling a cleavage stage embryo transferred 8 days later to implant. Either corpus luteum formation could be disrupted or the endometrium could remain unresponsive to progesterone during the early follicular phase.

Luteal phase ovarian stimulation following oocyte retrieval: is it helpful for poor responders?

BACKGROUND

Poor ovarian response and retrieval of no oocytes following ovarian stimulation for in vitro fertilization (IVF) is a challenging problem for both the patient and the clinician.

FINDINGS

Recent evidence indicates that folliculogenesis occurs in a wave-like fashion indicating that there are multiple follicular recruitment waves in the same menstrual cycle. This relatively new scientific concept provides new opportunities for the utilization of ovarian stimulation in women with poor ovarian response. This communication reports on the social and scientific rationale for the use of luteal phase ovarian stimulation following oocyte retrieval in the same cycle (also called double stimulation).

CONCLUSIONS

Data to date showed that double ovarian stimulation in poor responders provides shorter time for retrieving mature oocytes with the potential formation of good quality embryos, and thus healthy pregnancies.

Efficacy of random-start controlled ovarian stimulation in cancer patients

This study aimed to evaluate the efficacy of random-start controlled ovarian stimulation (COS) in cancer patients for emergency fertility preservation. In this retrospective comparative study, 22 patients diagnosed with cancer and 44 infertile women undergoing conventional in vitro fertilization (IVF) were included. In cancer patients, ovarian stimulation was started on the day of referral, irrespective of their menstrual cycle date. The control group was selected by age matching among women undergoing conventional IVF. COS outcomes were compared between groups. The number of total and mature oocytes retrieved and the oocyte maturity rate were higher in the random-start group than in the conventional-start group. However, duration of ovarian stimulation was longer in the random-start group (11.4 vs. 10.3 days, P = 0.004). The addition of letrozole to lower the estradiol level during COS did not adversely affect total oocytes retrieved. However, oocyte maturity rate was lower in cycles with letrozole than in cycles without letrozole (71.6% vs. 58.2%, P = 0.019). Our study confirms the feasibility and effectiveness of random-start COS in cancer patients.

Study of two strategies to induce follicular wave emergence for assisted reproductive treatments (ART)-a preliminary trial

PURPOSE

This study aimed to induce follicular wave emergence (FWE) using pharmacological (recombinant hCG administration) or mechanical (aspiration of dominant follicle) interventions in infertile women.

METHODS

Sixteen infertile women (≤35 years) with indications for in vitro fertilization due to tubal and/or male factor infertility were randomized into three groups: control (n = 6), pharmacological (n = 5) and mechanical (n = 5) groups. Women in both experimental groups underwent serial transvaginal sonograms (TVS) from menstrual cycle day 10 until identification of a dominant follicle ≥15 mm. Women in the pharmacological group received 250 μg of recombinant-hCG to induce ovulation, and resumed serial TVS 2 days later. In the mechanical group, dominant and subordinate follicles ≥10 mm were aspirated, and daily TVS was resumed on the following day. An increased pool of follicles ≥5 and ≤9 mm after interventions characterized FWE. Women in the control group underwent ovulation induction (OI) with 150 IU/day of recombinant follicle-stimulating hormone started on menstrual cycle day 3 (D3). OI was started on the day of FWE in the experimental groups. Endometrial asynchrony with development of the embryo was expected in the experimental groups. Therefore, all viable embryos were cryopreserved and transferred in an endometrial-stimulated cycle.

RESULTS

The number of follicles ≥5 and ≤9 mm increased after the interventions in both experimental groups (p < .001), indicating induction of FWE. OI outcomes were similar among the groups.

CONCLUSIONS

The pharmacological and mechanical interventions are efficient in inducing FWE; outcomes of OI synchronized with FWE should be further investigated.

Unpredicted ovulations and conceptions during early pregnancy: an explanatory mechanism of human superfetation

In this bioessay, a literature review on human superfetation was performed in order to find epidemiological variables associated with this phenomenon. Thereafter, an explanatory mechanism of superfetation compatible with the endocrinological, histological and physiological changes undergone by women during early pregnancy is proposed. Superfetation can be defined as the ovulation, fertilisation and implantation of a second or additional embryo(s) during pregnancy. The literature review evidences a small discordance in gestational age between dizygotic twins in humans (range: 2–4 weeks; mean ± s.e.m.: 3.3 ± 0.3 weeks). This difference is compatible with a luteal out-of-phase (LOOP; i.e. atypical increase in E2 levels in the mid-luteal phase)-like event occurring between 1 and 3 weeks after the ovulation that allowed the first pregnancy to take place. The LOOP-like event may allow passive sperm transport from the vaginal fornix to the Fallopian tube ipsilateral to the ovulatory ovary and trigger a LH peak and ovulation. Furthermore, during very early pregnancy, the decidual reaction is not yet completed and at least one proximal Fallopian ostium may be opened, allowing the passage of the spermatozoa ascending to the fertilisation site and the extra embryo(s) descending to the implantation site(s).

In vivo oocyte IGF-1 priming increases inner cell mass proliferation of in vitro-formed bovine blastocysts

Studies addressing the effects of supraphysiological levels of IGF-1 on oocyte developmental competence are relevant for unravelling conditions resulting in high bioavailability of IGF-1, such as the polycystic ovary syndrome (PCOS). This study investigated the effects of supraphysiological levels of IGF-1 during in vivo folliculogenesis on the morula-blastocyst transition in bovine embryos. Compacted morulae were non-surgically collected and frozen for subsequent mRNA expression analysis (IGF1R, IGBP3, TP53, AKT1, SLC2A1, SLC2A3, and SLC2A8), or underwent confocal microscopy analysis for protein localization (IGF1R and TP53), or were cultured in vitro for 24 h. In vitro-formed blastocysts were subjected to differential cell staining. The mRNA expression of SLC2A8 was higher in morulae collected from cows treated with IGF-1. Both IGF1R and TP53 protein were present in the plasma membrane and cytoplasm. IGF-1 treatment did not affect protein localization of both IGF1R and TP53. In vitro-formed blastocysts derived from morulae recovered from IGF-1-treated cows displayed a higher number of cells in the inner cell mass (ICM). Total cell number (TCN) of in vitro-formed blastocysts was not affected. A higher mean ICM/TCN proportion was observed in in vitro-formed blastocysts derived from morulae collected from cows treated with IGF-1. The percentage of in vitro-formed blastocysts displaying a low ICM/TCN proportion was decreased by IGF-1 treatment. In vitro-formed blastocysts with a high ICM/TCN proportion were only detected in IGF-1 treated cows. Results show that even a short in vivo exposure of oocytes to a supraphysiological IGF-1 microenvironment can increase ICM cell proliferation in vitro during the morula to blastocyst transition.