Effects of FSH addition to an enriched medium containing insulin and EGF after long-term culture on functionality of equine ovarian biopsy tissue

Croton grewioides essential oil and anethole reduce oxidative stress and improve growth of bovine primordial follicles during culture of ovarian tissue

OBJECTIVES

This study aims to evaluate the effects of Croton grewioides essential oil (CGEO) and anethole on follicle survival, growth, and oxidative stress in cultured bovine ovarian tissues.

METHODS

Ovarian tissues were cultured for 6 days in a medium supplemented with different concentrations (1, 10, 100, or 1000 µg mL-1) of CGEO or anethole and then, follicular survival and growth, collagen content, and stromal cell density in ovarian tissues cultured in vitro were evaluated by histology. The mRNA levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase 1 (GPX1), peroxirredoxin 6 (PRDX6), and nuclear factor erythroid 2-related factor 2 (NRF2) were evaluated by real-time PCR. The activity of SOD, CAT, glutathione peroxidase (GPx), and thiol concentrations were investigated.

KEY FINDINGS

Ovarian tissues cultured with 1 µg mL-1 CGEO or anethole had a higher percentage of healthy follicles than those cultured in a control medium (P < .05). The 1 µg mL-1 CGEO also increased the number of stromal cells, collagen fibers, and thiol levels. Anethole (1 µg mL-1) increased CAT activity and reduced that of GPx. The activity of SOD was reduced by CGEO. In contrast, 1 µg mL-1 anethole reduced mRNA for CAT, PRDX1, and NRF2 (P < .05). In addition, 1 µg mL-1 CGEO reduced mRNA for CAT, PRDX6, and GPx1 (P < .05).

CONCLUSIONS

The presence of 1 µg mL-1 anethole or CGEO in a culture medium promotes follicle survival and regulates oxidative stress and the expression of mRNA and activity of antioxidant enzymes in cultured bovine ovarian tissues.

Ethanol, Carnoy, and paraformaldehyde as fixative solutions for histological evaluation of preantral follicles in equine ovarian tissue

The most adequate fixative solution for equine ovarian tissue is still to be determined as a tool to evaluate the improvement of methodological studies in assisted reproductive techniques and fertility preservation. This study aimed to evaluate a short-time ethanol 70% (ST-EtOH, 45 min) exposure as an alternative fixative compared with two classically fixatives [Carnoy's (CAR) solution and paraformaldehyde 4% (PFA)] at different fixation times (6 h, 12 h). The end points evaluated were morphology and classes of preantral follicles, follicular and stromal cell densities, and follicular and oocyte nuclear diameters in equine ovarian tissue. Ovaries (n = 6) from ovariectomized young mares were fragmented (3 × 3 × 1 mm; 20 fragments/ovary) and fixed in the tested treatments. Overall, a total of 11,661 preantral follicles were evaluated in 1444 histological slides. The ST-EtOH similarly preserved the preantral follicle morphometry and stromal cell density compared to the PFA fixative, regardless of the exposure time. Nonetheless, the CAR fixative solution had the greatest percentage of normal preantral follicles and the highest stromal cell density among all treatments. In conclusion, Carnoy's solution must be preferred compared with ST-EtOH and PFA fixatives for studies concerning the cellular morphology of equine ovarian tissue. Moreover, ST-EtOH fixative is a good alternative for equine ovarian tissue when a quick histological evaluation is required instead of more time-consuming and expensive techniques. Additional studies concerning the impact of different fixatives on the ultrastructure of cellular populations and their compatibility with IHC and molecular techniques in equine ovarian tissue are warranted.

Current understanding of the genomic abnormities in premature ovarian failure: chance for early diagnosis and management

Premature ovarian failure (POF) is an insidious cause of female infertility and a devastating condition for women. POF also has a strong familial and heterogeneous genetic background. Management of POF is complicated by the variable etiology and presentation, which are generally characterized by abnormal hormone levels, gene instability and ovarian dysgenesis. To date, abnormal regulation associated with POF has been found in a small number of genes, including autosomal and sex chromosomal genes in folliculogenesis, granulosa cells, and oocytes. Due to the complex genomic contributions, ascertaining the exact causative mechanisms has been challenging in POF, and many pathogenic genomic characteristics have yet to be elucidated. However, emerging research has provided new insights into genomic variation in POF as well as novel etiological factors, pathogenic mechanisms and therapeutic intervention approaches. Meanwhile, scattered studies of transcriptional regulation revealed that ovarian cell function also depends on specific biomarker gene expression, which can influence protein activities, thus causing POF. In this review, we summarized the latest research and issues related to the genomic basis for POF and focused on insights gained from their biological effects and pathogenic mechanisms in POF. The present integrated studies of genomic variants, gene expression and related protein abnormalities were structured to establish the role of etiological genes associated with POF. In addition, we describe the design of some ongoing clinical trials that may suggest safe, feasible and effective approaches to improve the diagnosis and therapy of POF, such as Filgrastim, goserelin, resveratrol, natural plant antitoxin, Kuntai capsule et al. Understanding the candidate genomic characteristics in POF is beneficial for the early diagnosis of POF and provides appropriate methods for prevention and drug treatment. Additional efforts to clarify the POF genetic background are necessary and are beneficial for researchers and clinicians regarding genetic counseling and clinical practice. Taken together, recent genomic explorations have shown great potential to elucidate POF management in women and are stepping from the bench to the bedside.

The effect of bioidentical nanostructured progesterone in the in vitro culture of preantral follicles and oocyte maturation

This study evaluated the effects of bioidentical nanostructured progesterone alone or in association with human chorionic gonadotropin (hCG) on the in vitro survival and development of preantral follicles (experiment 1) and oocyte maturation (experiment 2). Bioidentical hormones have a molecular structure identical with that of endogenous hormones; nanostructured substances refer to those reduced to a nanoscale. In experiment 1, fragments of goat ovarian tissue were cultured for 7 days in α-MEM⁺ alone or supplemented with nanoprogesterone (MEM⁺ + P4) or P4 and hCG (MEM⁺ + P4 + hCG). In experiment 2, two mediums of oocyte in vitro maturation (IVM) were compared. Medium 1 consisted of TCM 199⁺ + LH, and medium 2 consisted of TCM 199⁺ with nanoprogesterone and hCG. The MEM⁺ + P4 + hCG treatment showed the lowest percentage of follicular survival after 7 days of culture. MEM⁺ + P4 and MEM⁺ + P4 + hCG treatments showed higher percentage of follicular activation than MEM⁺. In experiment 2, there were no differences between mediums 1 and 2 for all endpoints evaluated. In conclusion, the addition of nanoprogesterone is advisable for in vitro culture of preantral follicles and oocyte maturation. However, the association of nanoprogesterone with hCG causes the cellular death of initial follicles but shows efficacy in IVM.

Harvesting, processing, and evaluation of in vitro-manipulated equine preantral follicles: A review

The mammalian ovary is responsible for essential stages of folliculogenesis and hormonal production, regulating the female physiological functions during the menstrual/estrous cycles. The mare has been considered an attractive model for comparative studies due to the striking similarities shared with women regarding in vivo and in vitro folliculogenesis. The ovarian follicular population in horses contains a large number of oocytes enclosed in preantral follicles that are yet to be explored. Therefore, the in vitro manipulation of equine preantral follicles aims to avoid the process of atresia and promote the development of follicles with competent oocytes. In this regard, after ovarian tissue harvesting, the use of appropriate processing techniques, as well as suitable approaches to evaluating equine preantral follicles and ovarian tissue, are necessary. Although high-quality equine ovarian tissue can be obtained from several sources, some critical aspects, such as the age of the animals, ovarian cyclicity, reproductive phase, and the types of ovarian structures, should be considered. Therefore, this review will focus on providing an update on the most current advances concerning the critical factors able to influence equine preantral follicle quality and quantity. Also, the in vivo strategies used to harvest equine ovarian tissue, the approaches to manipulating ovarian tissue post-harvesting, the techniques for processing ovarian tissue, and the classical approaches used to evaluate preantral follicles will be discussed.

Supportive techniques to investigate in vitro culture and cryopreservation efficiencies of equine ovarian tissue: A review

During the reproductive lifespan of a female, only a limited quantity of oocytes are naturally ovulated; therefore, the mammalian ovary possesses a substantial population of preantral follicles available to be handled and explored in vitro. Hence, the manipulation of preantral follicles enclosed in ovarian tissue aims to recover a considerable population of oocytes of high-value animals for potential application in profitable assisted reproductive technologies (ARTs). For this purpose, the technique of preantral follicle in vitro culture (IVC) has been the most common research tool, achieving extraordinary results with offspring production in the mouse model. Although promising outcomes have been generated in livestock animals after IVC of preantral follicles, the quantity and quality of embryo production with those oocytes are still poor. In recent years, the mare has become an additional model for IVC studies due to remarkable similarities with women and livestock animals regarding in vivo and in vitro ovarian folliculogenesis. For a successful IVC system, several factors should be carefully considered to provide an optimum culture environment able to support the viability and growth of preantral follicles enclosed in ovarian tissue. The cryopreservation of the ovarian tissue is another important in vitro manipulation technique that has been used to preserve the reproductive potential in humans and, in the future, may be used in highly valuable domestic animals or endangered species. Several improvements in cryopreservation protocols are necessary to support the utilization of ovarian tissue of different species in follow-up ARTs (e.g., ovarian fragment transplantation). This review aims to provide an update on the most current advances regarding supportive in vitro techniques used in equids to evaluate and manipulate preantral follicles and ovarian tissue, as well as methodological approaches used during IVC and cryopreservation techniques.

Heterotopic ovarian allotransplantation in goats: Preantral follicle viability and tissue remodeling

An appropriate implantation site favors angiogenesis and avoids ovarian tissue damage after tissue grafting. The objective of this study was to evaluate the effects of intramuscular (IM) and subcutaneous (SC) sites for ovarian grafts in goats by evaluating follicular morphology and activation, preantral follicle and stromal cell densities, tissue DNA fragmentation, collagen types I and III depositions, and graft revascularizations. Ovarian cortical tissue was transplanted in IM or SC sites and recovered 7 or 15 days post-transplantation. There was a greater percentage of developing follicles and lesser follicular and stromal cell densities in all grafted tissues as compared to ovarian tissues of the control group. The stromal cell density and percentage of normal follicles were positively associated. At 15 days post-transplantation, tissues at the SC and IM sites had similar amounts of DNA fragmentation and type III collagen content. In contrast, tissues at the SC, as compared with IM site, had greater abundances of collagen type I. Furthermore, there was a positive association between collagen type I and percentage of morphologically normal follicles post-transplantation. In addition to a marked decrease in follicular density 15 days post-transplantation in ovarian grafts at the SC and IM sites, low percentages of normal follicles and follicular activation were observed similarly in both transplantation sites. There were also positive associations of stromal cell density and abundance of type I collagen fibers with the percentage of intact follicles in grafted ovarian tissues.

Deficiency in proliferative, angiogenic, and LH receptors in the follicle wall: implications of season toward the anovulatory condition

This study aimed to gain insight on the effect of different seasons of the year on the expression pattern of growth factor and hormone receptors involved in follicle development. A novel follicle wall biopsy technique was used to collect in vivo follicle wall layers (ie, granulosa, theca interna, and theca externa) and follicular fluid samples from growing dominant follicles, simultaneously and repeatedly, using the same mares during the spring anovulatory (SAN), spring ovulatory (SOV), summer (SU), and fall ovulatory (FOV) seasons. The immunofluorescent expression patterns of epidermal growth factor receptor (EGFR), Ki-67, vascular endothelial growth factor receptor (VEGFR), and LH receptor (LHR) were evaluated in each follicle wall layer, in addition to intrafollicular estradiol and nitric oxide (NO). Proliferative proteins (EGFR and Ki-67) were highly (P < 0.05-P < 0.001) expressed during the SOV season compared with the SAN and FOV seasons. Lower (P < 0.05-P < 0.001) expression of both proteins was observed during SU compared with the SOV season. The expression of VEGFR was greater (P < 0.05-P < 0.01) in the theca interna of dominant follicles during the SOV season compared with the SAN and SU seasons. Similarly, in the overall quantification, the VEGFR expression was greater (P < 0.001) during the SOV season compared with the SU and FOV seasons. A higher (P < 0.05) LHR expression was detected in the theca interna during the SOV season than the SAN season. Furthermore, a higher (P < 0.05-P < 0.001) expression of LHR was observed in the granulosa, theca interna, and in the overall quantification during the SOV season compared with the SU and FOV seasons. Intrafollicular NO concentration did not differ (P > 0.05) among different seasons of the year. The intrafollicular estradiol concentration was higher (P < 0.05) during the SU compared with the SAN season and higher (P < 0.05) during the FOV season compared with the SAN and SOV seasons. In conclusion, the synergistic effect of lower expression of proliferative protein, angiogenic, and LH receptors in at least some of the layers of the follicle wall seems to trigger dominant follicles toward the anovulation process during the spring and fall transitional seasons.

Powdered coconut water (ACP 406®) as an alternative base culture medium for in vitro culture of goat preantral follicles enclosed in ovarian tissue

This study evaluated a powdered coconut water solution (ACP 406®) as a base culture medium on the in vitro survival and development of in situ goat preantral follicles. The ovarian fragments were either immediately fixed in Carnoy solution (non-cultured control) or individually cultured for 2 or 6 days. The following culture media (all containing 100 μg/mL penicillin and 100 μg/mL streptomycin) were evaluated: α-MEM (α-MEM alone, without additional supplementation); α-MEM+ (supplemented α-MEM); ACP (ACP®406 alone); or ACP+ (supplemented ACP®406). Additional supplementation includes: 1.25 mg/mL bovine serum albumin, 10 μg/mL insulin, 5.5 μg/mL transferrin, 5 ng/mL selenium, 2 mM glutamine, and 2 mM hypoxanthine. The endpoints (i) follicular morphology; (ii) development; (iii) estradiol production; and (iv) reactive oxygen species (ROS) were recorded. Data were analyzed using chi-square, Turkey, t-test or One-Way ANOVA. Differences were considered significant when P < 0.05. At day 2 of culture, a greater (P < 0.05) percentage of morphologically normal follicles was observed between ACP+ and ACP treatments. Moreover, at day 2 of culture, no hormonal difference (P < 0.05) was observed between ACP+ and both α-MEM treatments. At day 6 of culture when ACP and α-MEM treatments were compared the percentage of healthy follicles were similar (P > 0.05) among treatments. Overall, all treatments had lower primordial follicles (P < 0.05) accompany by greater developing follicles (P < 0.05) percentages than non-cultured control treatment, indicating primordial follicle activation. However, at day 6 of culture, the percentage of primordial follicle development were similar (P > 0.05) among the treatments. Likewise, no differences (P > 0.05) were observed for ROS production and follicular and oocyte diameters among treatments. Therefore, ACP+ has the equivalent efficiency to MEM+ in maintaining the survival and development of goat preantral follicles, representing an alternative plant-based low-cost culture medium for in vitro culture.

Transition to the ovulatory season in mares: An investigation of antral follicle receptor gene expression in vivo

The inability to obtain in vivo samples of antral follicle wall layers without removing the ovaries or sacrificing the animals has limited more in-depth studies on folliculogenesis. In this study, a novel ultrasound-guided follicle wall biopsy (FWB) technique was used to obtain in vivo follicle wall layers and follicular fluid samples of growing antral follicles. The expression of proliferative, hormonal, angiogenic, and pro-/antiapoptotic receptors and proteins in the follicular wall among three follicle classes were compared during the spring transitional anovulatory (SAN) and spring ovulatory (SOV) seasons in mares. The main findings observed in the granulosa, theca interna, and/or all follicle layers during the SOV season compared with the SAN season were (a) small-sized follicles (10-14 mm) had greater epidermal growth factor receptor (EGFR) and Bcl-2 expression; (b) medium-sized follicles during the expected deviation/selection diameter (20-24 mm) had greater expression of EGFR, Ki-67, luteinizing hormone receptor (LHR), and Bcl-2; and (c) dominant follicles (30-34 mm) had greater EGFR, Ki-67, vascular endothelial growth factor, LHR, and Bcl-2 expression. Estradiol related receptor alpha expression and intrafollicular estradiol concentration increased, along with an increase in follicle diameter in both seasons. In this study, the application of the FWB technique allowed a direct comparison of different receptors' expression among follicles in different stages of development and between two seasons using the same individuals, without jeopardizing their ovarian function. The successful utilization of the FWB technique and the mare as an experimental animal offer a great combination for future folliculogenesis studies on mechanisms of follicle selection, development, and ovulation in different species, including women.

Natural antioxidants in the vitrification solution improve the ovine ovarian tissue preservation

The present study evaluated the effect of the addition of antioxidants anethole (AN) and robinin (RO) in the vitrification solution, and the in vitro incubation (IVI) medium of ovine ovarian tissue. Ovarian fragments were vitrified without antioxidant (VWA) or with different concentrations of AN (30, 300 and 2000 μg/mL) or RO (0.125, 0.25 and 0.50 mg/mL), followed by IVI (24 h). Histological analyses showed that the percentage of morphologically normal preantral follicles (MNPF) in AN 2000 did not differ from RO 0.125 or fresh ovarian tissue (CTR). Subsequently, ovarian fragments were vitrified in the presence of AN 2000 and RO 0.125 followed by IVI without or with (AN 2000+ and RO 0.125+) the same antioxidants. The follicular activation in all treatments was significantly increased as compared to the CTR. The stroma cell density (SCD) in all the vitrified fragments was significantly lower than the CTR. However, in the AN 2000 and RO 0.125 this parameter was significantly higher when compared to the VWA. The reactive oxygen species (ROS) in the ovarian cortex of the AN 2000 or AN 2000+ were significantly reduced in comparison with the CTR while the intracellular ROS levels of AN 2000 and CTR were similar. The total antioxidant capacity (TAC) in RO 0.125 was significantly higher than that of VWA, AN 2000 and AN 2000+. According to the results, the use of antioxidants (AN or RO) only in the vitrification solution of ovine ovarian tissue is recommended, due to their better preservation of the SCD. Moreover, AN 2000 best maintains the follicular morphology, while RO 0.125 has a high TAC.

Laparoscopic ovarian biopsy pick-up method for goats

Biopsy pick-up (BPU) has been considered a safe method to harvest ovarian fragments from live animals. However, no studies have been reported on the use of BPU to collect in vivo ovarian tissue in goats. The goals of this study were: (i) to test different biopsy needle sizes to collect ovarian tissue in situ using the BPU method (Experiment 1), and (ii) to study ovarian tissue features such as preantral follicle density, morphology, class distribution, and stromal cell density in ovarian fragments obtained in vivo through a laparoscopic BPU method (Experiment 2). In Experiment 1, goat ovaries (n = 20) were collected in a slaughterhouse and subjected to in situ BPU. Three needles (16, 18, and 20G) were tested. In Experiment 2, the most efficient biopsy needle from Experiment 1 was used to perform laparoscopic BPU in goats (n = 8). In Experiment 1, the recovery rate was greater (P < 0.05; range 50-62%) with 16G and 18G needles than the 20G (17%) needle. The mean weight of ovarian fragments collected by the 16G needle was greater (P < 0.05) than the 18G and the 20G needle. In Experiment 2, 62 biopsy attempts were performed and 52 ovarian fragments were collected (90% success rate). Overall, 2054 preantral follicles were recorded in 5882 histological sections analyzed. Mean preantral follicular density was 28.4 ± 1.3 follicles per cm². The follicular density differed (P < 0.05) among animals and ovarian fragments within the same animal. The mean stromal cell density in the ovarian fragments was 37.1 ± 0.5 cells per 2500 μm², and differed (P < 0.05) among animals. Moreover, preantral follicle density and stromal cell density were associated (P < 0.001). The percentage of morphologically normal follicles was 70.1 ± 1.2, and differed (P < 0.05) among animals. The majority (79%) of the morphologically normal follicles was classified as primordial follicles, and differed (P < 0.05) among animals and between ovaries. In summary, a laparoscopic BPU method has been developed to harvest ovarian tissue in vivo with a satisfactory success rate in goats. Furthermore, this study described for the first time that goat ovarian biopsy fragments have a high heterogeneity in follicular density, morphology, class distribution, and stromal cell density.