Transcriptional downregulation of ABC transporters is related to follicular degeneration after vitrification and in vitro culture of ovine ovarian tissue.

ATP-binding cassette (ABC) transporters perform multiple functions in reproductive tissues. During ovarian tissue vitrification, the plasma membrane has important functions in the influx or efflux of water, and substances such as cryoprotectants and channel proteins that are required in this process. Thus, the present study aimed to verify the relative abundance of mRNA transcript of ABC transporters ABCB1, ABCG2, and MRP2 after vitrification and in vitro culture (IVC) of ovine ovarian tissue. For this study, the ovarian cortex fragments were proportioned into four groups as fresh control, vitrified control, fresh culture, and vitrified culture groups. After vitrification and in vitro culture, the ovarian tissue was evaluated using morphological procedures. Further, relative abundance of ABCB1, ABCG2, and MRP2 transporter mRNA transcripts in the ovarian cortex subjected to aforementioned treatment conditions were evaluated using qPCR. Our results showed a negative association between degenerated follicles and mRNA transcript abundances of ABCB1 and ABCG2. In addition, the percentage of growing follicles in the ovine ovarian cortex after vitrification was similar to that of the fresh control tissue without in vitro culture. The in vitro culture of fresh and vitrified tissue however, showed a significant decrease in the percentage of growing follicles. To the best of our knowledge, we believe that our data for the first time has studied the relative abundances of ABCB1 and ABCG2 mRNA transcripts in the ovine ovarian cortex. In addition, alterations of these protein channels may be indicative of a deleterious effect of osmotic stress on follicular survival during vitrification. Furthermore, these effects were detectable only after the IVC of the ovarian tissues. Nonetheless, further studies are required to investigate the functions of ABC transporters in ovine folliculogenesis, especially after in vitro culture of ovarian tissue.

In vivo and in vitro strategies to support caprine preantral follicle development after ovarian tissue vitrification.

The aim of the present study was to compare fresh and vitrified goat ovarian tissue after autotransplantation and in vitro culture. Adult goats were completely ovariectomised and each ovarian pair was sliced and distributed among six different treatment groups: fresh control, fresh transplant, fresh culture, vitrified control, vitrified transplant and vitrified culture. Follicular morphology, development, growth, density, revascularisation and hormone production were evaluated in all groups. Three antral follicles (two in the fresh transplant and one in the vitrified transplant groups) were observed on the surface of the graft 90 days after transplantation. The percentage of morphologically normal follicles was similar in the fresh control, fresh transplant and vitrified transplant groups. The percentage of developing (transition, primary and secondary) follicles was higher after in vitro culture of fresh or vitrified tissue. Transplantation resulted in a lower follicle density. Serum oestradiol concentrations remained constant during the entire transplantation period. In contrast, progesterone production decreased significantly. Expression of CD31 mRNA was lower in fresh culture. In conclusion, restoration of goat ovarian function can be successfully achieved following transplantation of both fresh and vitrified goat ovarian tissue. However, transplantation induced higher follicle loss than in vitro culture.

Anti-Müllerian hormone reduces growth rate without altering follicular survival in isolated caprine preantral follicles cultured in vitro.

The aim of the present study was to evaluate the effect of anti-Müllerian hormone (AMH), with and without FSH, on the in vitro development of isolated caprine preantral follicles, as well as follicular steroid production and mRNA levels of AMH, hormone receptors (AMH and FSH), CYP19A1 (cytochrome P450, family 19, subfamily A, polypeptide 1), CYP17 (cytochrome P450, family 17, subfamily A, polypeptide 1), HSD3B (3-beta-hydroxysteroid dehydrogenase) and Myc (myelocytomatosis oncogene). Isolated secondary follicles were cultured in minimum essential medium alpha (α-MEM+) alone or supplemented with 50ng mL-1 AMH and/or 100ng mL-1 FSH added sequentially on different days of culture. Follicles were cultured for a total of 18 days, with different media during the first (Days 0-9) and second (Days 10-18) halves of the culture period, resulting in six treatment groups, as follows: α-MEM+/α-MEM+, FSH/FSH, AMH/AMH, AMH+FSH/AMH+FSH, AMH/FSH, and FSH/AMH. Follicle development was evaluated on the basis of follicular growth, oocyte maturation and steroid secretion. There was a decrease in follicular growth rate in the AMH, AMH+FSH and AMH/FSH treatment groups compared with α-MEM+ and FSH treatment groups (P<0.05). However, the different culture conditions had no effect on rates of meiotic resumption and steroid secretion (P>0.05). Moreover, follicles cultured in the presence of FSH had lower levels of AMH receptor type II (AMHRII) mRNA compared with non-cultured control (freshly isolated follicles), and the AMH and AMH/FSH treatment groups. In conclusion, AMH reduces the follicular growth rate of isolated goat preantral follicles in vitro without affecting follicular survival.

Comparison between the additive effects of diluted (rFSH) and diluted/dynamized (FSH 6 cH) recombinant follicle-stimulating hormone on the in vitro culture of ovine preantral follicles enclosed in ovarian tissue.

OBJECTIVE: This study compared 2 types of recombinant follicle stimulating hormone (rFSH): diluted and diluted/dynamized, on in vitro development of ovine follicles. METHODS: In experiment 1, ovarian fragments were cultured for 1 or 7 days in α-MEM(+) in the absence or presence of different concentrations of diluted rFSH to determine the best concentration. In experiment 2, the effect of diluted and diluted/dynamized rFSH (rFSH 6 cH--ultradiluted and succussioned), alone or in combination, was studied. RESULTS: In experiment 1, compared to control, 50ng/mL of diluted rFSH induced higher rates of follicular survival after 7 days of culture and higher percentages of growing follicles at day 1 of culture (P<0.05). In experiment 2, compared to control, diluted/dynamized rFSH induced higher follicular diameter and survival rate after 7 days and early follicle activation at day 1 of culture (P<0.05). Compared to diluted rFSH, diluted/dynamized rFSH induced higher rates of follicle activation at day 1 of culture (P<0.05). CONCLUSION: In conclusion, compared to the control medium, diluted/dynamized rFSH promoted survival and early activation of follicles, while diluted rFSH promoted higher activation later in the culture. Thus, diluted/dynamized rFSH may be used as an alternative to diluted rFSH for the in vitro culture of ovine preantral follicles.

Immunolocalization of the Anti-Müllerian Hormone (AMH) in Caprine Follicles and the Effects of AMH on In Vitro Culture of Caprine Pre-antral Follicles Enclosed in Ovarian Tissue.

The aims of this study were to evaluate the localization, by immunohistochemistry, of the anti-Müllerian hormone (AMH) in goat ovaries and to investigate its effects on the in vitro survival and development of caprine pre-antral follicles enclosed in fragments of ovarian tissue. Pre-antral follicles were cultured in vitro for 1 or 7 days in α-MEM(+) in the absence or presence of kit ligand (KL; 50 ng/ml, positive control) or AMH (50 or 150 ng/ml). The results showed that AMH was localized in oocytes and granulosa cells from the primordial follicle to antral follicle stages. Addition of AMH maintained the percentage of developing follicles, similar to that in the uncultured control; however, the percentage of developing follicles was significantly lower than that in the cultured control and KL. Nonetheless, addition of AMH to the culture medium did not affect survival rates and follicular growth. In conclusion, this study demonstrated that the expression of AMH varies according to the compartment and stage of follicular development. Furthermore, AMH inhibits the activation of caprine primordial follicles.

FSH supplementation to culture medium is beneficial for activation and survival of preantral follicles enclosed in equine ovarian tissue.

This study investigated the effect of adding different concentrations of bovine recombinant follicle-stimulating hormone on the IVC of equine preantral follicles enclosed in ovarian tissue fragments. Randomized ovarian fragments were fixed immediately (fresh noncultured control) or cultured for 1 or 7 days in α-MEM(+) supplemented with 0, 10, 50, and 100 ng/mL FSH and subsequently analyzed by classical histology. Culture media collected on Day 1 or Day 7 and were analyzed for steroids (estradiol and progesterone) and reactive oxygen species (ROS). After Day 1 and Day 7 of culture, 50-ng/mL FSH treatment had a greater (P < 0.05) percentage of morphologically normal follicles when compared to the other groups, except the 10-ng/mL FSH treatment at Day 1 of culture. The percentage of developing follicles (transition, primary, and secondary), and follicular and oocyte diameters were higher (P < 0.05) in the 50-ng/mL FSH treatment compared to the other groups after Day 7 of culture. Furthermore, estradiol secretion and ROS production were maintained (P > 0.05) throughout the culture in the 50-ng/mL FSH treatment. In conclusion, the addition of 50 ng/mL of FSH promoted activation of primordial follicles to developing follicles, improved survival of preantral follicles, and maintained estradiol and ROS production of equine ovarian tissue after 7 days of culture.

Insulin improves in vitro survival of equine preantral follicles enclosed in ovarian tissue and reduces reactive oxygen species production after culture.

This study investigated the effect of insulin concentration on the in vitro culture of equine preantral follicles enclosed in ovarian tissue. Ovarian tissue samples were immediately fixed (noncultured control) or cultured for 1 or 7 days in α-MEM(+) supplemented with 0 ng/mL, 10 ng/mL, or 10 µg/mL insulin. Ovarian tissues were processed and analyzed by classical histology. Culture medium samples were collected after 1 and 7 days of culture for steroid and reactive oxygen species (ROS) analyses. The percentage of morphologically normal follicles was greater (P < 0.001) in insulin-treated groups after 1 day of culture; likewise, more (P < 0.02) normal follicles were observed after 7 days of culture in medium supplemented with 10-ng/mL insulin. Furthermore, an increase (P < 0.01) in developing (transition, primary, and secondary) follicles between Days 1 and 7 of culture was observed only with the 10-ng/mL insulin treatment. ROS production after 1 or 7 days of culture was lower (P < 0.0001) in medium with 10-ng/mL insulin than the other treatments. Ovarian tissues containing preantral follicles were able to produce estradiol and progesterone after 1 and 7 days of culture; however, treatments did not differ in steroid production. In conclusion, the use of a physiological concentration (10 ng/mL) of insulin rather than the previously reported concentration (10 µg/mL) for in vitro culture of equine preantral follicles improved follicular survival and growth and lowered oxidative stress. Results from this study shed light on new perspectives for producing an appropriate medium to improve equine preantral follicle in vitro survival and growth.

Is the mouse follicle culture a good model for the goat with respect to the development of preantral follicles in vitro?

The present study evaluated the efficiency of using 2 culture media developed for mice and for goats in the in vitro preantral follicle culture of each species. Murine and caprine secondary follicles were cultured in vitro with human recombinant follicle-stimulating hormone (murine medium) or with bovine recombinant follicle-stimulating hormone in association with growth hormone (caprine medium). The results showed that murine follicles cultured in caprine medium had lower (P < 0.05) rates of follicular survival and growth, whereas for caprine follicles, these variables were not affected by the type of medium used (P > 0.05). After in vitro maturation, a higher (P < 0.05) number of oocytes that resumed meiosis were observed in the murine medium for both species. In contrast, only in the caprine species estradiol production was significantly superior when the caprine medium was used. Higher progesterone production was observed in the presence of the murine medium only for murine follicles (P < 0.05). In conclusion, murine and caprine preantral follicles cultured under the same in vitro culture medium conditions respond differently; caprine oocytes grown in vitro in the presence of the murine medium show the greatest developmental competence among the tested combinations. Therefore, under the present experimental conditions, the mouse follicle culture has proved be a good model for the development of new culture media for caprine preantral follicles.

Effect of morphological integrity, period, and type of culture system on the in vitro development of isolated caprine preantral follicles.

The aims of this study were the following: (1) to define an optimal period for the IVC of isolated caprine preantral follicles, (2) to verify the relationship between follicular morphology (intact, extruded, and degenerate follicles) and estradiol production, and (3) to evaluate the effects of the bidimensional (2D) and three-dimensional (3D) culture systems on the in vitro development of caprine preantral follicles. Three experiments were performed. In experiments 1 and 2, the isolated secondary follicles were cultured for 18, 24, and 30 days or 30, 36, and 42 days, respectively. In experiment 3, the optimal culture period from experiment 2 was used for 2D and 3D culture systems. After culture, the oocytes were submitted to IVM. The morphological integrity, antral cavity formation rates, follicular diameter, presence of healthy, grown oocytes (≥110 µm), rates of resumption of meiosis, and estradiol concentrations were evaluated. In experiment 1, the percentage of oocytes that resumed meiosis was higher in oocytes cultured for 30 days (48.84%) than in oocytes cultured for 18 and 24 days (15% and 20.93%, respectively). In experiment 2, the percentage of oocytes that resumed meiosis was significantly higher in oocytes cultured for 30 and 36 days (47.5% and 50%, respectively) than in oocytes cultured for 42 days (20%). The estradiol concentrations on Day 12 of culture were similar for normal and extruded follicles and higher than those observed in degenerate follicles at the end of the culture period. In conclusion, the 36-day culture period resulted in the highest rates of meiosis resumption. In addition, because the loss of follicular integrity affects the patterns of estradiol production, follicular integrity is a good predictor of follicular quality.

Interaction between melatonin and follicle-stimulating hormone promotes in vitro development of caprine preantral follicles.

The aim of this study was to investigate the effects of melatonin and follicle-stimulating hormone (FSH) on the in vitro culture of goat preantral follicles. Ovarian fragments were cultured for 7 d in α-minimum essential medium (α-MEM(+)) containing melatonin (100, 250, 500, or 1,000 pM), FSH (50 ng/mL), or a combination of the 2 hormones and further analyzed by histology and transmission electron and fluorescent microscopy. The results showed that after 7 d of culture, tissues cultured in α-MEM(+) alone or supplemented with FSH alone, melatonin (500 and 1,000 pM), or the combination of FSH and melatonin (1,000 pM) maintained percentages of normal preantral follicles similar to the fresh control. In contrast to the noncultured tissues, the percentage of developing follicles was increased under all culture conditions after 7 d (P < 0.05). The addition of 1,000 pM melatonin associated with FSH to the culture medium increased follicular and oocyte diameters compared with α-MEM(+) alone after 7 d of culture (P < 0.05). Ultrastructural and fluorescent analyses confirmed the integrity of follicles cultured with 1,000 pM of melatonin plus FSH for 7 d. In conclusion, this study demonstrated that the interaction between melatonin and FSH maintains ultrastructural integrity and stimulates further growth of cultured caprine preantral follicles.

Dynamic medium containing growth differentiation factor-9 and FSH maintains survival and promotes in vitro growth of caprine preantral follicles after long-term in vitro culture.

The aim of the present study was to evaluate the effects of growth differentiation factor 9 (GDF-9) and FSH on the in vitro development of caprine preantral follicles cultured for 16 days. Ovarian fragments were cultured in αMEM⁺ (α-minimum essential medium, pH 7.2-7.4, 10 µg mL⁻¹ insulin, 5.5 µg mL⁻¹ transferrin, 5.0 ng mL⁻¹ selenium, 2 mM glutamine, 2 mM hypoxanthine and 1.25 mg mL⁻¹ bovine serum albumin) in the absence or presence of 200 ng mL⁻¹ GDF-9 and/or 50 ng mL⁻¹ FSH added during the first (Days 0-8) and/or second (Days 8-16) half of the culture period. Non-cultured and cultured fragments were processed for histological and ultrastructural analyses. After 16 days, all treatments using GDF-9 or FSH showed higher rates of follicular survival compared with αMEM⁺ alone. Compared with non-cultured control, sequential culture media containing GDF-9 and/or FSH significantly increased the percentage of developing follicles and follicle diameter. Moreover, a progressive increase in oocyte diameter was observed only with sequential culture medium containing GDF-9 until Day 8 followed by FSH (GDF-9/FSH) in the second half of the culture period. After 16 days of culture, ultrastructural analysis confirmed the integrity of follicles cultured in the presence of GDF-9/FSH. In conclusion, a dynamic medium containing GDF-9 and FSH (GDF-9/FSH) maintained follicular integrity and promoted activation of primordial follicles and growth during long-term in vitro culture of goat preantral follicles.

In vitro development of primordial follicles after long-term culture of goat ovarian tissue.

This study aims to investigate the effects of follicle stimulating hormone (FSH) and fibroblast growth factor-2 (FGF-2) on the survival and growth of caprine preantral follicles. Ovarian tissues were cultured for 1, 7, 14, 21 or 28 days in medium supplemented with FSH (FSH-2d or FSH-7d, i.e., with replacement of the culture medium every 2 or 7 days, respectively) or FSH+FGF-2 (replacement of the medium every 2 days). Non-cultured (control) and cultured ovarian fragments were processed for histological and ultrastructural analysis. After 28 days of culture, the media supplemented with FSH-2d was the most effective in maintaining the percentage of normal follicles and in promoting follicular growth. Furthermore, both treatments with FSH increased the percentage of the primary follicles. However, ultrastructural studies did not confirm follicular integrity from 14 days of culture onward. In conclusion, culturing tissue for up to 7 days in medium containing FSH alone or combined with FGF-2 maintains caprine preantral follicle integrity and promotes their growth in vitro.

Follicle stimulating hormone and fibroblast growth factor-2 interact and promote goat primordial follicle development in vitro.

The aims of the present study were to investigate the effects of the interaction between follicle stimulating hormone (FSH) and fibroblast growth factor-2 (FGF-2) on survival, follicular growth initiation and further growth of caprine preantral follicles. Pieces of caprine ovarian cortex were cultured for 1 or 7 days in minimum essential medium (MEM) supplemented with FSH, FGF-2 or FSH + FGF-2. Small fragments from non-cultured ovarian tissue and from those cultured for 1 or 7 days were processed for classical histology and transmission electron microscopy (TEM) to verify follicular morphology and growth. The results showed that, after 7 days culture, the highest percentages of normal follicles were observed in medium supplemented with FSH. After 7 days culture, the interaction between FSH and FGF-2 was most effective to promote the initiation of primordial follicles growth and oocyte growth. TEM showed ultrastructural integrity of follicles after 1 day of culture in MEM and after 7 days in all treatments, except in those follicles cultured for 7 days in MEM. In conclusion, this study demonstrated that the interaction between FSH and FGF-2 stimulates the initiation of primordial follicles growth and the subsequent growth of developing follicles. Furthermore, these data showed that FSH is important to maintain follicular integrity after 7 days culture.