scholarly journals Extract of Amburana cearensis maintains the survival of ovine preantral follicles during long-term ovarian tissue transport and promotes primordial follicle activation after in vitro culture

2018 ◽  
Vol 39 (5) ◽  
pp. 2001
Author(s):  
Vanúzia Gonçalves Menezes ◽  
Ricássio De Sousa Barberino ◽  
Bruna Bortoloni Gouveia ◽  
Rodrigo José de Souza Gonçalves ◽  
Jackson Roberto Guedes da Silva Almeida ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Culture Medium ◽  
Ovarian Tissue ◽  
Primordial Follicle ◽  
Chi Square ◽  
Preantral Follicles ◽  
Primordial Follicle Activation ◽  
Chi Square Test

This study evaluated the effect of Amburana cearensis extract as a preservation or culture medium for ovine ovarian tissue. Ovarian fragments were fixed in 4% buffered formaldehyde for 18 h (fresh control), stored in Minimal Essential Medium (MEM) or in A. cearensis extract (0.1; 0.2 or 0.4 mg/mL) at a temperature of 4ºC for 6, 12 or 24 h (preservation - experiment 1) or cultured for 7 days in ?-MEM+ or in A. cearensis extract without (0.1; 0.2 or 0.4 mg/mL) or with supplements (0.1+ ; 0.2+ or 0.4+ mg/ mL; experiment 2). The percentages of morphologically normal follicles and follicular activation were submitted to analysis of variance (ANOVA) and Tukey´s test. The values of TUNEL-positive cells were submitted to Chi-square test (P < 0.05). The storage of fragments for 6 h in MEM showed higher percentages of normal follicles (62%) and a lower rate of TUNEL positive cells (36.17%) compared to other treatments (normal follicles: 46%; 43% and 52%; TUNEL positive cells: 58.57%; 55.30% and 55.63% for Amb 0.1; Amb 0.2 and Amb 0.4 mg/mL, respectively). However, after 12 or 24 h, MEM (12 h: 48%; 24 h: 45%) and Amb 0.2 mg/mL (12 h: 37%; 24 h: 39%) showed similar percentages of normal follicles and TUNEL positive cells (MEM - 12 h: 43.26%; 24 h: 58%; Amb 0.2 mg/mL - 12 h: 50%; 24 h: 61%). After culture, ?-MEM+ recorded a higher percentage of normal follicles (58.25%) than A. cearensis treatments (32.8%; 25.4% and 34.2% for Amb 0.1; Amb 0.2 and Amb 0.4 mg/mL, and 22.25%; 20.0% and 36.6% for Amb 0.1+ ; Amb 0.2+ and Amb 0.4+ mg/mL, respectively) (P < 0.05). Follicular activation increased in all treatments (52.5%; 36.73%; 54.05%; 47.5% and 58.19% for ?-MEM+ ; Amb 0.1; Amb 0.1+ ; Amb 0.2+ and Amb 0.4+ mg/mL, respectively) compared to the fresh control (11.65%), except for Amb 0.2 mg/mL (23.69%) and Amb 0.4 mg/mL (28.85%) (P > 0.05). Moreover, after in vitro culture, A. cearensis at a concentration of 0.1 mg/mL maintained the percentage of TUNEL positive cells (30.0%) in a way that is similar to that observed in the fresh control (22%) (P > 0.05). In conclusion, ovine preantral follicles can be preserved at 4°C in MEM for 6 h. For longer periods of preservation (24 h), MEM and 0.2 mg/mL A. cearensis are recommended. Moreover, after in vitro culture, A. cearensis extract (0.1 mg/mL) showed higher activation and lower DNA fragmentation in ovine preantral follicles.

325 VIABILITY AND GROWTH OF CATTLE PREANTRAL FOLLICLES AFTER IN VITRO CULTURE OF OVARIAN FRAGMENTS IN α-TOCOPHEROL

2010 ◽  
Vol 22 (1) ◽  
pp. 318 ◽  
Author(s):  
L. A. Lisboa ◽  
E. R. Andrade ◽  
M. F. Hertel ◽  
F. A. Melo-Sterza ◽  
K. Moreno ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Ovarian Tissue ◽  
Nuclear Antigen ◽  
Cortical Tissue ◽  
Chi Square ◽  
Primordial Follicles ◽  
Preantral Follicles ◽  
Chi Square Test ◽  
Proliferating Cell

The development of culture systems to support the initiation of growth of primordial follicles is important to the study of the factors that control the earliest stages of folliculogenesis. The aims of the present study were to investigate the effects of α-tocopherol on survival, activation, and growth of cattle preantral follicles using histological and immunohistochemistry proliferating cell nuclear antigen (PCNA) studies. The ovarian cortex was divided into small fragments; one fragment was immediately fixed in Bouin (control). The other fragments were cultured for 2, 4, 6, or 8 d in culture plates with Minimum Essential Medium supplemented with insulin-transferrin-selenium (ITS), pyruvate, glutamine, hypoxanthine, BSA, and antibiotics (MEM+); and MEM+ plus α-tocopherol (5, 25, 50, 100, or 200 ng mL-1). Preantral follicles were classified according to their developmental stage (primordial, intermediate, primary, or secondary) and on the basis of morphological features (normal or degenerated). Pair-wise comparisons were done using Tukey’s procedure. Chi-square test was used to compare the percentage of follicles with PCNA-positive granulosa cells. All analyses were done with the SAS software (SAS Institute, Cary, NC, USA), and P < 0.05 was considered significant. The results showed that, compared with non-cultured cortical tissue (Day 0), the culture of ovarian tissue significantly reduced (P < 0.05) the percentage of normal follicles in all media tested, except for tissue cultured in the presence of 200 ng mL-1 of a-tocopherol. Furthermore, in all media tested, the percentage of primordial follicles was significantly reduced (P < 0.05), with a concomitant increase in the percentage of developing follicles. The highest percentage of secondary follicles was observed after 6 days of culture in MEM plus 200 ng mL-1 of a-tocopherol. The PCNA analysis confirmed the viability of follicles cultured with 200 ng mL-1 of a-tocopherol after 6 d. After 8 days of in vitro culture, we observed severe follicular degeneration in all media tested, suggesting that other supplements are recommended for longer periods of culture. In conclusion, the results of the present study indicate that 200 ng mL-1 of a-tocopherol maintains the survival of cattle preantral follicles and promotes activation of primordial follicles after 6 days of in vitro culture. Financial support: L. A. Lisboa is a recipient of CAPES support; E. R. Andrade and A. A. Alfieri are recipients of PRODOC/CAPES fellowships.

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

2019 ◽  
Vol 16 (4) ◽  
pp. 838-845
Author(s):  
Olga Juliana Roldan Castañeda ◽  
Francisco Léo Nascimento de Aguiar ◽  
Naiza Arcângela Ribeiro de Sá ◽  
Maria Luana Galdencio dos Santos Morais ◽  
Francielli Weber Santos Cibin ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Culture Medium ◽  
Ovarian Tissue ◽  
Coconut Water ◽  
Preantral Follicles

scholarly journals Patient with ovarian insufficiency: baby born after anticancer therapy and re-transplantation of cryopreserved ovarian tissue

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Vladimir Isachenko ◽  
Bernd Morgenstern ◽  
Plamen Todorov ◽  
Evgenia Isachenko ◽  
Peter Mallmann ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Ovarian Tissue ◽  
Primordial Follicle ◽  
Anticancer Therapy ◽  
Primary Follicle ◽  
Ovarian Insufficiency ◽  
Cryopreserved Ovarian Tissue ◽  
Long Term Prognosis

Abstract Background The second major cause of death is cancer. In fact, the effectiveness of anticancer treatments and positive long-term prognosis for young women has increased. However, the problem of post-cancer infertility plays a significant role, because chemotherapy can be gonadotoxic and lead to the functional death of ovaries. There is potential key solution to this problem: cryopreservation of ovarian tissue before cancer therapy with re-implantation after convalescence. Data regarding cryopreservation and re-transplantation of ovarian tissue from patients with ovarian insufficiency is limited. The aim of this treatment was the re-transplantation of cryopreserved ovarian tissue after anticancer therapy of patient with ovarian insufficiency (56 IU/l FSH, 8 ng/l β-estradiol, < 1.1 ng/ml anti-Mullerian hormone, 1 primary follicle per 10mm3). Case presentation After the operation, four tissue fragments (10–16 × 8–13 × 1.0–1.2 mm) were cooled to 5 °C in the freezing medium (culture medium+ 6% ethylene glycol+ 6% dimethyl sulfoxide+ 0.15 M sucrose) for 24 h, frozen and thawed. Freezing was performed in four standard 5 ml cryo-vials with ice formation at − 9 °C, cooling from − 9 to − 34 °C at a rate of − 0.3 °C/min and plunging at − 34 °C into liquid nitrogen. After thawing in a 100 °C (boiling) water bath, the removal of cryoprotectants was performed in 0.5 M sucrose with 20 min. exposure in sucrose and 30 min. stepping rehydration. After thawing of one cryo-vial, part (5 mm3) of experimental ovarian tissue after 7 day in vitro culture was histological evaluated and two ovarian fragments (8 × 7 × 1.0 mm and 7 × 6 × 1.0 mm) were re-transplanted. The quantity of follicles after cryopreservation and in vitro culture was not increased (P > 0.1): it was found 1 primordial follicle in 5 mm3 of tissue. Thirty seven days after the re-transplantation of ovarian tissue, the restoration of the menstrual cycle of Patient W. was noted. Three months after the transplantation, the patient became spontaneously pregnant and delivered a healthy baby girl at term. Conclusions Described protocol of conventional cryopreservation of ovarian tissue can be used for treatment of patients with ovarian insufficiency.

scholarly journals In-vitro fragmentation of ovarian tissue activates primordial follicles through the Hippo pathway

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
C De Roo ◽  
S Lierman ◽  
K Tilleman ◽  
P De Sutter
Keyword(s):  
Tissue Culture ◽  
Ovarian Tissue ◽  
Hippo Pathway ◽  
Primordial Follicle ◽  
Akt Pathway ◽  
Primordial Follicles ◽  
Primordial Follicle Activation ◽  
The Hippo Pathway ◽  
Follicle Activation

Abstract STUDY QUESTION What is the role of the Hippo and PI3K/Akt pathway in follicles during ovarian tissue culture in tissue derived from oncological patients and transgender men? SUMMARY ANSWER Results highlight a Hippo pathway driven primordial follicle activation in vitro, predominantly from Day 0 to Day 4. WHAT IS KNOWN ALREADY In-vitro ovarian tissue culture aims at activating and maturing primordial follicles for fertility restoration in patients with a threatened ovarian reserve. Not all patients are eligible for ovarian cortex transplantation and therefore several groups are attempting to culture ovarian tissue in-vitro. Cortex fragmentation disrupts the Hippo pathway, leading to increased expression of downstream growth factors and follicle growth. The PI3K/Akt pathway is considered the intracellular pathway to where different extracellular factors involved in primordial follicle activation in-vivo converge. In order to optimise current ovarian tissue culture models, information on progression of these pathways during tissue culture is mandatory. STUDY DESIGN, SIZE, DURATION The first step of a multistep cortex culture system was performed using 144 ovarian cortex pieces from a total of six patients. Per patient, 24 cortical strips were cultured for 6 days and six pieces per patient were collected for downstream analysis of follicle development and Hippo and PI3K/Akt pathway targets every second day. PARTICIPANTS/MATERIALS, SETTING, METHODS Ovarian tissue was obtained from oncological (N = 3; 28.67 ± 4.51 years) and transgender (N = 3; 23.33 ± 1.53 years) patients. Follicles were analysed using haematoxylin-eosin staining and pathways were studied using immunohistochemistry and precise follicle excision by laser capture micro-dissection for RT-qPCR analysis. MIQE guidelines for RT-qPCR were pursued. Reference gene selection (GAPDH, RPL3A, 18s rRNA) was performed using GeNorm Reference Gene Selection Kit. Statistical analysis was conducted with IBM SPSS Statistics 23 (Poisson regression, negative binomial regression, ANOVA and paired t-test). MAIN RESULTS AND THE ROLE OF CHANCE Immunohistochemical analysis confirmed a Hippo pathway driven primordial follicle activation due to mechanical manipulation of the cortical strips. Ovarian tissue preparation and culture induced the inhibitory phosphorylated Yes-associated protein (pYAP) to disappear in granulosa cells of primordial follicles on Day 2. The stimulatory YAP on the contrary appeared in primordial granulosa cells over increasing culture days. Looking at the YAP target connective tissue growth factor (CTGF), a significantly up-regulated CTGF was noted in primordial follicles when comparing Day 2 and Day 4 (ratio Day 2/4 = 0.082; P &lt; 0.05), clearly showing an effect on the Hippo pathway in primordial follicles during tissue culture. Follicle classification showed a significant drop in estimated primordial follicle counts in the oncological cohort (−78%; P = 0.021) on Day 2 and in the transgender cohort on Day 4 (−634%; P = 0.008). Intermediate follicle counts showed a non-significant increasing trend to during culture and this follicle recruitment and growth resulted in a significant rise in estimated primary follicle counts on Day 6 in oncological patients (170%; P = 0.025) and, although limited in absolute numbers, a significant increase in secondary follicles on Day 4 (367%; P = 0.021) in the transgender cohort. Subsequent antral follicle development could not be observed. LIMITATIONS, REASONS FOR CAUTION A limitation is the small sample size, inherent to this study subject, especially as a large amount of tissue was needed per patient to reduce inter-patient variation in different downstream analysis techniques. A particular and specific weakness of this study is the inability to include an age-matched control group. WIDER IMPLICATIONS OF THE FINDINGS These findings support an adapted tissue preparation for Hippo pathway disruption and a shorter first phase of tissue culture. This work may also have implications for transplantation of cryopreserved tissue as larger strips (and thus slower burnout due to less Hippo pathway disruption) could be a benefit. STUDY FUNDING/COMPETING INTEREST(S) This research was financially supported by the Foundation Against Cancer (Stichting tegen Kanker, TBMT001816N), the Flemish Foundation of Scientific Research (FWO Vlaanderen, FWO G0.065.11N10) and the Gender Identity Research and Education Society (GIRES) foundation. The authors declare no competing interests. TRIAL REGISTRATION NUMBER N/A.

Slush nitrogen vitrification of human ovarian tissue does not alter gene expression and improves follicle health and progression in long-term in vitro culture

2018 ◽  
Vol 110 (7) ◽  
pp. 1356-1366 ◽  
Author(s):  
Vincenza Barbato ◽  
Roberto Gualtieri ◽  
Teresa Capriglione ◽  
Maria Michela Pallotta ◽  
Sabrina Braun ◽  
...  
Keyword(s):  
Gene Expression ◽  
In Vitro Culture ◽  
Ovarian Tissue ◽  
Human Ovarian Tissue

scholarly journals In vitro follicle culture in the context of IVF

Reproduction ◽  
2018 ◽  
Vol 156 (1) ◽  
pp. F59-F73 ◽  
Author(s):  
Anamaria C Herta ◽  
Francesca Lolicato ◽  
Johan E J Smitz
Keyword(s):  
Fertility Preservation ◽  
Polycystic Ovary ◽  
Ovarian Tissue ◽  
Primordial Follicle ◽  
Assisted Reproduction Techniques ◽  
Realistic Potential ◽  
Primordial Follicles ◽  
Primordial Follicle Activation ◽  
Extracellular Matrix Components

The currently available assisted reproduction techniques for fertility preservation (i.e.in vitromaturation (IVM) andin vitrofertilization) are insufficient as stand-alone procedures as only few reproductive cells can be conserved with these techniques. Oocytes in primordial follicles are well suited to survive the cryopreservation procedure and of use as valuable starting material for fertilization, on the condition that these could be grown up to fully matured oocytes. Our understanding of the biological mechanisms directing primordial follicle activation has increased over the last years and this knowledge has paved the way toward clinical applications. New multistepin vitrosystems are making use of purified precursor cells and extracellular matrix components and by applying bio-printing technologies, an adequate follicular niche can be built. IVM of human oocytes is clinically applied in patients with polycystic ovary/polycystic ovary syndrome; related knowhow could become useful for fertility preservation and for patients with maturation failure and follicle-stimulating hormone resistance. The expectations from the research on human ovarian tissue and immature oocytes cultures, in combination with the improved vitrification methods, are high as these technologies can offer realistic potential for fertility preservation.

P-444 Presence of pharmacological inhibitors of the PI3K/PTEN/Akt and mTOR signalling pathways during cryopreservation and organotypic cultures of murine ovaries limits early primordial follicle depletion

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
C Terren ◽  
M Nisolle ◽  
C Munaut
Keyword(s):  
In Vitro Culture ◽  
Organotypic Culture ◽  
Primordial Follicle ◽  
Slow Freezing ◽  
Signalling Pathways ◽  
Primordial Follicle Activation ◽  
Mtor Signalling ◽  
Follicle Activation

Abstract Study question Which signalling pathways are implicated in primordial follicle activation induced by cryopreservation and/or organotypic culture? Is it possible to limit this activation through pharmacological inhibitors? Summary answer Our findings provide support for the hypothesis that mTOR and PI3K inhibitors might represent an attractive tool to delay cryopreservation- and culture-induced primordial follicle activation. What is known already Cryopreservation of ovarian tissue containing immature primordial follicles followed by auto-transplantation (OTCTP) is the only option available to preserve the fertility of prepubertal patients or patients requiring urgent therapy for aggressive malignancies. However, a major obstacle in this process is follicular loss immediately after grafting, possibly due to slow neovascularization, apoptosis and/or massive follicular recruitment. In vitro and in vivo studies indicate that the PI3K/PTEN/Akt and mTOR signalling pathways are involved in follicle activation. The transplantation process seems to be the major cause of primordial follicle activation after OTCTP but information about how cryopreservation itself impacts follicle activation is sparse. Study design, size, duration Whole murine ovaries (4-8-weeks old) were cryopreserved by slow freezing and exposed to LY294002 (a powerful PI3K inhibitor) or rapamycin (a specific mTOR inhibitor) during cryopreservation and/or organotypic in vitro culture for a 24 h or 2 days. Participants/materials, setting, methods Western Blot and immunofluorescence analyses were used to determine the activation of PI3K/PTEN/Akt and mTOR signalling pathways in murine ovaries cryopreserved and/or organotypically cultured with/without inhibitors.Follicles were quantified according to their maturation degree on H&E stained histological sections.  Main results and the role of chance Ratio of phosphorylated Akt or rps6 to total proteins (p-Akt/Akt and p-rps6/rps6) was increased in slow-frozen murine ovaries compared to control fresh ovaries, indicating an activation of the PI3K/PTEN/Akt and mTOR signalling pathways. The use of pharmacological inhibitors of follicle signalling pathways (LY294002 (25µM) and rapamycin (1µM)) during the cryopreservation process decreased p-Akt/Akt and p-rps6/rps6 ratios. In vitro organotypic culture for 24 h increased only the activation of the PI3K/PTEN/Akt pathway, as shown by increased p-Akt/Akt ratio in fresh ovaries cultured for 24 h compared to fresh non-cultured ovaries. This activation can be counteracted by cryopreservation of murine ovaries with rapamycin followed by in vitro culture for 24 h in the presence of LY294002. Follicle density quantifications indicated that when cryopreserved ovaries were maintained in culture for 2 days, a decrease of primordial follicle density concomitant with an increase of secondary and more mature follicles were found in comparison to slow-frozen/thawed ovaries without culture. Supplementation of the culture medium with LY294002 and rapamycin for 24 h or 2 days preserved primordial follicle densities compared to ovaries cultured without inhibitors. Limitations, reasons for caution This study is an in vitro study using murine ovaries. To analyze the efficiency of LY294002 and rapamycin to limit cryopreservation and transplantation induced follicle recruitment, these inhibitors should be tested in an in vivo model. Furthermore, these findings will need to be confirmed with human samples. Wider implications of the findings We showed for the first-time that the sequential use of pharmacological inhibitors, rapamycin during the slow freezing process followed by organotypic culture supplemented with LY294002, is effective to limit early primordial follicle depletion. Trial registration number /

136 COMPARISON OF NCSU-23 AND ALPHA-MINIMAL ESSENTIAL MEDIA IN THE DEVELOPMENT OF ISOLATED PORCINE PREANTRAL FOLLICLES IN VITRO

2016 ◽  
Vol 28 (2) ◽  
pp. 198
Author(s):  
M. Rubessa ◽  
R. Rocha ◽  
L. Lima ◽  
R. Winters ◽  
J. R. Figueiredo ◽  
...  
Keyword(s):  
Culture Medium ◽  
Positive Trend ◽  
Minimal Essential Medium ◽  
Hormone Production ◽  
Chi Square ◽  
Preantral Follicles ◽  
Porcine Serum ◽  
Follicle Size ◽  
Α Level

To develop a preantral follicular culture system that will support follicular growth and result in fertilizable oocytes, we conducted an experiment designed to determine the best medium for culture. In our preliminary experiment, we compared 2 common base media used for porcine oocytes: α-minimal essential medium and NCSU-23. Ovaries were collected from prepubertal gilts at a local abattoir and transported to the laboratory in saline solution (0.9% NaCl) maintained at 30–35°C. The ovaries were cut into small pieces (1–3 mm), and preantral follicles were isolated mechanically. Preantral follicles from 280 to 300 μm in diameter were collected into a small dish containing medium TCM199 (Lonza 12–117F) supplemented with 5% fetal bovine serum. The follicles were transferred from the collecting medium to the culture medium that consisted of base medium (NCSU23 or α-minimal essential medium) supplemented with 3.5 μg mL–1 of insulin, 10 μg mL–1 of transferrin, 100 μg mL–1 of l-ascorbic acid, 7.5% porcine serum, and 1.5 ng mL–1 of FSH. The follicles were randomly distributed to the different experimental treatments and cultured for 6 days in 24-well cell culture plates, with 3 follicles per well in 280 μL of culture medium. The culture was carried out at 38.5°C in 5% CO2 in air. Culture medium was changed every 2 days with freshly prepared medium. The diameters of follicles were measured every 2 days, and each follicle was photographed and evaluated at 20× magnification. Forty-two follicles per group were analysed and collected in 4 replicates. Data were statistically analysed with ANOVA using the Generalized Linear Model (GLM) procedure (SPSS, version 18, SPSS Inc., Chicago, IL, USA), where the independent variable was the sample (group and day of culture). Tukey's post hoc test was used to perform multiple comparisons; the α level was set at 0.05. All data were expressed as quadratic means with standard error of the means. Only the antrum formation was evaluated by chi-square test. The results, reported in Table 1, show that there was no statistical differences between follicle size between NCSU23 or α-minimal essential media, but at Day 6 there was a positive trend (P = 0.08). Otherwise, when we compared the size inside the groups, we observed that the preantral follicles grew more in α-minimal essential media than in NCSU23. The percentages of antrum formation were 65 v. 76% (NCSU23 and α-minimal essential media, respectively). These results support the use of α-minimal essential media because it had a positive effect on the antrum formation, and that after Day 4 some follicles could undergo a regression phase. Future studies will be necessary to evaluate the molecular status and the hormone production. Table 1.Follicle size (μm) from Day 0 to Day 6

202 EFFECTS OF ASCORBIC ACID ON IN VITRO CULTURE OF CATTLE PREANTRAL FOLLICLES

2010 ◽  
Vol 22 (1) ◽  
pp. 259
Author(s):  
E. R. Andrade ◽  
R. van den Hurk ◽  
L. A. Lisboa ◽  
M. F. Hertel ◽  
F. A. Melo-Sterza ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
In Vitro Culture ◽  
Ovarian Tissue ◽  
Immunohistochemical Analysis ◽  
Development Stage ◽  
Nuclear Antigen ◽  
Primordial Follicles ◽  
Preantral Follicles ◽  
Ovarian Cortex

The mechanisms that regulate the gradual exit of ovarian follicles from the nongrowing, primordial pool are poorly understood. The objective of this study was to evaluate the effects of adding ascorbic acid to the media for in vitro culture of cattle ovarian fragments and to determine the effects of this addition on the growth activation and viability of preantral follicles. The ovarian cortex was divided into small fragments; 1 fragment was immediately fixed in Bouin’s solution (control). The other fragments were cultured for 2, 4, 6, or 8 days on culture plates in minimum essential medium (MEM) supplemented with insulin-transferrin-selenium (ITS), pyruvate, glutamine, hypoxantine, BSA, and antibiotics (MEM+) or in MEM+ plus ascorbic acid (5, 25, 50, 100, or 200 μg mL-1). Ovarian tissue was processed for classical histology, TEM, and immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA). Preantral follicles were classified according to their development stage (primordial, intermediate, primary, and secondary) and on the basis of morphological features (normal or degenerated). Pair-wise comparisons were done using Tukey’s procedure. Chi-square test was used to compare percentages of follicles with PCNA-positive granulosa cells. All analyses were done with Statistical Analysis System (SAS Institute, Cary, NC, USA); P ≤ 0.05 was considered significant. Compared with control fragments, the percentage of primordial follicles was reduced (P ≤ 0.05) and the percentage of growing follicles was increased (P ≤ 0.05) in cultured cortical fragments, independent of the tested medium or incubation time. Furthermore, compared with control tissue, culture of ovarian cortex for 8 days reduced the percentages of healthy, viable follicles (P ≤0.05), but not when cultures were supplemented with 25, 50, and 100 μg mL-1 of ascorbic acid. Ultrastructural and immunohistochemical analysis of ovarian cortical fragments cultured for 8 days, however, showed the integrity and viability of follicles only when fragments were cultured in the presence of 50 μg mL-1 of ascorbic acid. In conclusion, this study demonstrated that addition of ascorbic acid to MEM at a concentration of 50 μg mL-1 not only stimulates the activation and subsequent growth of cattle primordial follicles that are cultured in vitro for 8 days but also safeguards the viability of these preantral follicles. E. R. Andrade and A. A. Alfieri are recipients of the PRODOC/CAPES fellowship.

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