Morphology Of Preantral Follicles Research Articles

Cystic endometrial hyperplasia-pyometra syndrome impairs the preantral follicle reserve in domestic bitches (Canis familiaris)

Cystic endometrial hyperplasia (CEH)-pyometra syndrome is the most common uterine pathological condition reported in breeding bitches, however, their described effects on fertility are limited to uterine disorders and conception rates. As the preantral follicle population represents the available reserve of gametes recruited during the lifespan, the aim of this study was to evaluate the effects of CEH-pyometra syndrome on the: (i) preantral follicle morphology, (ii) developing follicle rates, and (iii) preantral follicle and stromal cell densities. Ovarian fragments from bitches subjected to elective or therapeutic ovariohysterectomy were allocated according to uterine diagnosis as follows: control (n = 7, clinically healthy), CEH-mucometra (n = 8, uterine lumen filled with a sterile mucus), and pyometra (n = 17, presence of a purulent mucus) groups. Overall, the control group had 3.4 and 4.1-fold higher probability (P < 0.0001) of the presence of normal preantral follicles compared with CEH-mucometra and pyometra groups, respectively. Moreover, ovarian fragments from the pyometra group showed an increase in the percentage of developing follicles (P < 0.05) compared to the control. Both CEH-mucometra and pyometra groups showed lower (P < 0.05) preantral follicle and stromal cell densities (P < 0.05) compared to the control. In summary, the CEH-pyometra syndrome decreased the percentage of morphologically normal follicles and enhanced the developing follicle rates. Additionally, a reduction of preantral follicle and stromal cell densities suggests that the inappropriate uterine environment induced by CEH-pyometra syndrome can lead to premature depletion of ovarian reserve.

Microbiological load and preantral follicle preservation using different systems for ovarian tissue vitrification in the red-rumped agouti

We evaluated the effect of open and closed systems used for ovarian tissue vitrification on the microbiological load and preservation of preantral follicles (PAFs) in the red-rumped agoutis. The ovaries from eight females were recovered and fragmented, with four cortexes fragments immediately fixed and evaluated (fresh group). The other fragments were processed for the solid-surface vitrification method (SSV) or an ovarian tissue cryosystem (OTC) using fetal calf serum, ethylene glycol, and sucrose as cryoprotectants, stored for two weeks, and rewarmed. Subsequently, fragments were subjected to a 24-h in vitro culture and assessed for microbiological load, PAF morphology, and DNA integrity. There was no fungal contamination; however, the vitrified samples from two individuals showed bacterial contamination of 79 200 colony forming units per milliliter (CFU)/mL for SSV and 3120 CFU/mL for OTC. From those samples, a total of eight different types of bacterial colonies were isolated and identified as coagulase-negative Staphylococci and Gram-positive bacilli. Regarding PAF morphology, both systems provided adequate preservation, with values higher than 70% normal follicles observed before and after culture. The TUNEL assay revealed that both SSV (52.39%) and OTC (41.67%) could preserve DNA integrity after vitrification and after 24 h of culture. In summary, both open and closed systems were equally efficient in preserving agouti ovarian tissues, especially concerning the preantral follicle morphology and DNA integrity; however, the OTC seems to provide a less adequate environment for bacterial proliferation.

87 Population estimate and morphology of ovarian preantral follicles in fetal and adult alpacas (Vicugna pacos)

Preantral follicles are the largest ovarian follicle population and represent an important source of potentially competent oocytes. During the lifespan of the female this large population becomes atretic during their growth. In alpacas, there are few studies that estimate the number of preantral follicles. Therefore, the objective of the present study was to compare the population and morphology of preantral follicles in the ovaries of fetal and adult alpacas. Ovaries from alpacas in fetal (fetus during the last third of gestation, n=5) and adult stage (3–4 years, n=5) were collected at a local slaughterhouse. The whole ovaries were individually fixed overnight at room temperature, and later dehydrated in alcohol, cleared with xylene, and embedded in paraffin. Tissue were sectioned at 7μm with a rotating microtome. Then, sections were processed and stained with periodic acid Schiff and haematoxylin. Preantral follicles were classified for their development stage as primordial, transitional, primary, or secondary, according to the layer number and form of granulosa cells. Estimation of the number of preantral follicles was made by counting all follicles in each histological section. Only follicles in which the oocyte nucleus was visible were counted. In addition, for each follicle category (n=30 per group), oocyte and follicle diameters were measured using Motic Images Plus 2.0 software. The population estimate and follicular diameter were compared using Kruskal–Wallis test with significance set at P ≤ 0.05 using SPSS v.2 2 software (IBM Corp.). A total of 2174 histologic sections were analysed. The results showed a higher (P=0.045) number of preantral follicles (80 516.1±3623.9) for fetal alpacas compared with adult alpacas (67 870.8±2267.4). Also, primordial follicles population (31 543.4±2690) and morphologically normal follicles (98.2%) were higher (P=0.04) in fetus compared with those in the adult stage (2244.7±355.37; 76.35%) respectively. On the contrary, the diameters of primordial, transitional, and primary follicles (45.34±3.76; 52.38±6.22; 59.79±5.22µm) from adult alpaca were greater (P=0.04) than those of fetal preantral follicles (33.305±7.2; 36.715±3; 77.985±15.8µm). In conclusion, the preantral follicle population declines dramatically in adult alpaca and animals of this age show an increased percentage of degenerate primordial follicles.

Response of preantral follicles exposed to quinoxaline: A new compound with anticancer potential

The culture of preantral follicles as an in vitro model to evaluate the toxicity of new anticancer drug has being established. Therefore, the aim of this study was to evaluate the effect of quinoxaline derivative the 2 2- (XYZC 6H 3 –CH=N-NH)-quinoxaline, 1 (QX) on caprine preantral follicles. We evaluate the follicular morphology and activation, proliferation and apoptosis of granulosa cells and finally the protein (ABCB1) and genes expression (cyclin/Cdks), respectively involved in multidrug resistance and cell cycle progression. Ovarian fragments containing primordial and developing follicles were exposed (in vitro culture) to different concentrations of QX (QX1.5, QX3.0 or QX6.0 μM/mL) during 6 days. To evaluate the effect of QX, the ovarian tissue was exposed to Paclitaxel 0.1 μg/mL (PTX – negative control) or in culture media without QX (MEM). At the end of exposure time, we realized that the QX (all concentrations) increased (P < .05) the normal morphology of preantral follicles compared to control (not treated ovarian tissue) or MEM. However, QX6.0 showed a enhanced (P < .05) on follicular activation (burnout) and apoptosis than QX1.5 and QX3.0. Expression of ABCB1 was similar between QX1.5 and QX6.0 and both were lower than control, MEM and PTX. Interestingly, the apoptosis rate in QX3.0 was similar to control and MEM and lower then QX1.5; QX6.0 and PTX. We conclude that quinoxaline may be a promising chemotherapeutic agent, however, other concentrations within a defined range (2–5.5 μM) could be widely investigated.

Survival of isolated human preantral follicles after vitrification: Analyses of morphology and Fas ligand and caspase-3 mRNA expression.

ObjectiveThis study aimed to examine the effect of vitrification on apoptosis and survival in human preantral follicles after thawing.MethodsThis experimental study was conducted at an acute tertiary care hospital from March 2012 to April 2013. Ovaries were sliced into 5×5×1-mm pieces and divided into the following three groups: preantral follicle isolation, ovarian tissue vitrification-warming followed by follicle isolation, and immunohistochemistry of fresh ovarian tissue. For statistical analyses, the Student t-test, chi-square test, Kruskal-Wallis test, and Kaplan-Meier survival analysis were used.ResultsA total of 161 preantral follicles (70% secondary) were collected from ovarian cortex tissue of six women between 30 and 37 years of age who underwent oophorectomy due to cervical cancer or breast cancer. There were no significant differences in the follicular morphology of fresh preantral follicles and vitrified follicles after thawing. The mean Fas ligand (FasL) mRNA expression level was 0.43±0.20 (relative to β-actin) in fresh preantral follicles versus 0.51±0.20 in vitrified follicles (p=0.22). The mean caspase-3 mRNA expression level in fresh preantral follicles was 0.56±0.49 vs. 0.27±0.21 in vitrified follicles (p=0.233). One vitrified-thawed secondary follicle grew and developed to an antral follicle within 6 days of culture.ConclusionVitrification did not affect preantral follicle morphology or mRNA expression of the apoptosis markers FasL and caspase-3. Further studies are required to establish whether vitrification affects the outcomes of in vitro culture and the maturation of preantral follicles.

Growth and Differentiation Factor-9 Supplementation Affects Viability and Morphology of Preantral Follicles in Equine Ovarian Fragments During Short-term in vitro Culture

Abstract This study aimed to evaluate different concentrations of growth and differentiation factor-9 (GDF-9) on the development and maintenance of equine preantral follicle morphology during short-term in vitro culture. Ovaries (n=5) from five mares were collected from a local slaughterhouse and transported to the laboratory, where nine fragments (5x5x1mm) were procured from each ovary. One fragment from each was immediately fixed and submitted for histological analysis (control group; D0). The other eight fragments were cultured in situ for two (D2) or six (D6) days in MEM+ or MEM+ supplemented with GDF-9 at different concentrations (i.e., 50, 100 and 200 ng/mL the GDF-9). After culturing with different concentrations of GDF-9 for 2 or 6 days, the fragments were processed for histological analysis. After two days of cultivation, we observed an increase in the percentage of developing follicles for 0 (MEM+), 50, 100 and 200 ng/mL GDF-9 compared to control (D0; P<0.05). When we evaluated all treatments that preserved follicular integrity, the GDF-9 concentration of 100 ng/mL presented results superior to those of the other cultures (P<0.05). While, at six days of culture, the concentration of 200 ng/mL of GDF-9 appeared to be more efficient in providing development compared to MEM+ (P<0.05). The percentage of morphologically intact follicles in the 6 days culture samples treated with 50 ng/mL of GDF-9 indicated that this concentration was effective in maintaining the integrity of the follicle (P<0.05). We conclude, therefore, that graduated GDF-9 addition to the medium ensure follicular development and is sufficient maintain the architecture.

Effect of cryopreservation techniques on proliferation and apoptosis of cultured equine ovarian tissue

Preservation of cellular integrity and its mechanisms after ovarian tissue cryopreservation (OTC) and in vitro culture (IVC) procedures are crucial aspects for the success of preservation and recovery of female fertility. This study aimed to evaluate the effects of two cryopreservation methods (slow-freezing, SF, and vitrification, VIT) on the equine ovarian tissue after 1, 3, and 7 days of IVC by assessing: (i) preantral follicle morphology and distribution of follicle classes; (ii) protein expression of markers of cell proliferation for EGFR and Ki-67; (iii) markers of apoptosis for Bax and Bcl-2; and (iv) DNA fragmentation. Percentages of normal primordial follicles were similar (P > 0.05) among SF-control, VIT-control, and fresh control groups. After 7 days of culture, VIT-IVC7 had a greater (P < 0.05) total percentage of normal preantral follicles when compared with SF-IVC7, but both had a lower (P < 0.05) percentage than fresh IVC7 group. Prior to and after 7 days of culture, expression of EGFR and Ki-67 were similar (P > 0.05) among fresh, SF, and VIT groups. After 7 days of culture, VIT had higher (P < 0.05) Bax expression than the fresh and SF tissues, but Bcl-2 was similar (P > 0.05) among groups. Prior to IVC, TUNEL signals were similar (P > 0.05) among groups; however, VIT-IVC7 had greater (P < 0.05) TUNEL signals when compared with the fresh IVC7 group. In conclusion, findings demonstrated: (i) similar efficiency between SF and VIT compared with fresh control to preserve morphologically normal follicles; and (ii) similar tissue functionality and cell proliferation capability after equine OTC by either SF and VIT methods following IVC for 7 days. The results herein presented shed light on equine fertility preservation programs using OTC techniques.

Xenotransplantation of goat ovary as an alternative to analyse follicles after vitrification.

The aim of this study was to evaluate the caprine preantral follicles enclosed on vitrified/warmed ovarian cortex grafted to nude BALB/mice during 1month. The ovarian cortex from goats was fragmented (3×3×0.5mm) and divided into four groups: fresh control, vitrified control, fresh transplant and vitrified transplant. Follicular morphology, development and density, fibrosis as well as apoptosis, and tissue revascularization were evaluated. It was also observed a significant decrease in morphologically normal preantral (primordial, transition, primary and secondary) follicles in both vitrified control and vitrified transplant treatments when compared with both fresh control and fresh transplant. However, fresh control and fresh transplant exhibited a similar percentage of developing follicles. Additionally, Vitrified control showed a significant increase in developing follicles in comparison with both fresh control and fresh transplant. Follicular density significantly decreased in all treatments in comparison with fresh control. We observed high fibrosis in both fresh transplant and vitrified transplant. The mRNA expression of caspase 3 was lower in both fresh transplant and vitrified transplant in comparison with vitrified control. In conclusion, xenotransplantation is an excellent strategy to maintain normal preantral follicle morphology after vitrification/warming of goat ovarian tissue. Yet, in order to ensure the survival and development of these follicles, it is essential to improve the revascularization of the graft.

Cat ovarian follicle ultrastructure after cryopreservation with ethylene glycol and dimethyl sulfoxide

Ovarian tissue cryopreservation is a promising technique for fertility maintenance. The aim of this study was to compare the morphology of domestic cat ovarian follicles after tissue cryopreservation with ethylene glycol (EG) and dimethyl sulfoxide (Me2SO). Ovaries from healthy adult cats undergoing elective ovariohysterectomy were used. Eight fragments were obtained from each pair of ovaries: two were used as fresh controls; three were submitted to fresh perfusion toxicity test and perfused with M199, 10% fetal calf serum and 0.4% sucrose containing Me2SO 1.5 M, EG 1.5 M or Me2SO 0.75 M + EG 0.75 M; and the remaining three fragments were perfused as described and submitted to slow freezing. After 45 days of cryopreservation, the samples were thawed, fixed and processed for light and transmission electron microscopy (TEM). The percentages of morphologically normal follicles identified by light microscopy were higher in the control group (94.45%) in comparison to the frozen groups (80.56% with EG, 78.7% with Me2SO and 75.87% with EG + Me2SO). The fresh perfused tissue showed no statistical difference compared to control or frozen samples. The TEM analysis showed less damage in the ultrastructure of follicles from the Me2SO group in comparison with the EG and Me2SO + EG groups. According to the morphological analysis, 1.5 M Me2SO is the best cryoprotectant for cryopreservation of domestic cat ovarian tissue regarding the morphology of preantral follicles after thawing. Further studies regarding the viability of these follicles should be performed.

Cryopreservation and in vitro culture of white-tailed deer ovarian tissue

The aims of this study were to evaluate (1) the survivability of white-tailed deer ovarian tissue after cryopreservation by slow-freezing (SF) and vitrification (VIT) techniques and in vitro culture (IVC) for up to 7 days, and (2) the effects of cryopreservation techniques on protein expression of proliferative and apoptotic markers of ovarian tissue pre- and post-in vitro culture. Ovaries (n = 14) of seven white-tailed deer fawns (<1.5 years old) were used. Ovarian cortexes were cut into fragments (2 × 2 × 0.5 mm) and split into nine treatment groups: (1) fresh noncultured control, (2) fresh-IVC 1 day, (3) fresh-IVC 7 days, (4) SF noncultured, (5) SF-IVC 1 day, (6) SF-IVC 7 days, (7) VIT noncultured, (8) VIT-IVC 1 day, and (9) VIT-IVC 7 days. Preantral follicle morphology, class distribution, and density; stromal cell density; EGFR, Ki-67, Bax, and Bcl-2 protein expression; and DNA fragmentation were assessed. Results showed that: (i) white-tailed deer fresh ovarian tissue can be cultured for up to 7 days, preserving the tissue integrity and 50% of morphologically normal preantral follicles; (ii) cryopreservation of white-tailed deer ovarian tissue by either slow-freezing or vitrification does not disrupt markers of proliferation and apoptosis after thawing; (iii) ovarian fragments cryopreserved by the vitrification method had greater follicle viability during in vitro culture than the slow-freezing method; and (iv) fragments cryopreserved by slow-freezing suffered apoptosis earlier than those preserved by vitrification. The findings herein reported advance knowledge towards development of adequate cryopreservation protocols for long-term banking programs for Cervidae species.

Alpha lipoic acid (ALA) effects on developmental competence of equine preantral follicles in short-term culture

The effect of different concentrations of alpha lipoic acid (ALA) on the development and morphology of preantral follicles, as well as the proliferative activity of granulosa cells, was assessed after short-term culture. Ovaries (n = 5) of five seasonal anestrous mares were harvested in a local abattoir. At the laboratory, nine ovarian fragments (5 × 5 × 1 mm) from each animal were used. One fragment was immediately fixed in Bouin and subjected to histological and immunohistochemistry (proliferating cell nuclear antigen, PCNA) analyses (noncultured group; D0 = day 0). The other eight fragments were cultured in situ for two (D2) or six (D6) days in MEM+ or MEM+ plus ALA (50, 100, or 250 μM). After culture, fragments were subjected to histology and PCNA analyses. After two days of culture, ALA 50 and ALA 100 had the greatest (P < 0.05) percentage of normal primordial follicles (97.2 and 95.1%, respectively), when compared to other groups, and did not differ (P > 0.05) from the fresh noncultured control group. Furthermore, the total percentage of normal follicles was greater (P < 0.05) in the ALA 50 and ALA 100 than in the MEM-D2 group. After six days of culture, the highest (P < 0.05) proliferative activity of granulosa cells in developing follicles was observed for the groups MEM+ (92.9%), ALA 50 (100%), and ALA 100 (96.4%). In conclusion, the results of this study demonstrated that (1) ALA 50 and ALA 100 preserved the morphological integrity of equine primordial follicles for up two days of culture, and (2) granulosa cells of developing follicles enclosed in ovarian tissue and cultured for up to six days in MEM+ with or without ALA were highly stained by PCNA.

Ovarian features in white-tailed deer (Odocoileus virginianus) fawns and does.

The knowledge about ovarian reserve is essential to determine the reproductive potential and to improve the methods of fertility control for overpopulated species, such as white-tailed deer (Odocoileus virginianus). The goal of this study was to evaluate the effect of age on the female reproductive tract of white-tailed deer, focusing on ovarian features. Genital tracts from 8 prepubertal and 10 pubertal females were used to characterize the preantral follicle population and density, morphology, distribution of follicular classes; stromal cell density; and apoptosis in the ovary. In addition, uterus and ovary weights and dimensions were recorded; and the number and the size of antral follicles and corpus luteum in the ovary were quantified. Overall, fawns had a greater (P < 0.05) preantral follicle population, percentage of normal follicles, and preantral follicle density than does. The mean stromal cell density in ovaries of fawns and does differed among animals but not between age groups. The apoptotic signaling did not differ (P > 0.05) between the ovaries of fawns and does. However, apoptotic ovarian cells negatively (P < 0.001) affected the preantral follicle morphology and density, and conversely, a positive correlation was observed with stromal cell density. As expected, the uteri and ovaries were larger (P < 0.002) and heavier (P < 0.001) in does than in fawns. In conclusion, this study has shown, for the first time, the preantral follicle population and distribution of classes, rate of morphologically normal follicles, and density of preantral follicles and stromal cells in white- tailed deer. Therefore, the findings herein described lead to a better understanding of the white-tailed deer ovarian biology, facilitating the development of new methods of fertility control.

Equine ovarian tissue viability after cryopreservation and in vitro culture

Ovarian tissue cryopreservation allows the preservation of the female fertility potential for an undetermined period. The objectives of this study were to compare the efficiency of cryoprotective agents (CPAs; dimethyl sulfoxide, DMSO; ethylene glycol, EG; and propylene glycol, PROH) using slow-freezing and vitrification methods, and evaluate the viability of cryopreserved equine ovarian tissue after 7 days of culture. Fresh and cryopreserved ovarian fragments were evaluated for preantral follicle morphology, stromal cell density, EGFR, Ki-67, Bax, and Bcl-2 protein expression, and DNA fragmentation. Vitrification with EG had the highest rate of morphologically normal preantral follicles, while DMSO had the lowest (76.1 ± 6.1% and 40.9 ± 14.8%, respectively; P < 0.05). In slow-freezing, despite that DMSO had the highest percentage of morphologically normal follicles (77.7 ± 5.8%), no difference among the CPAs was observed. Fluorescence intensity of EGFR and Ki-67 was greater when vitrification with EG was used. Regardless of the cryopreservation treatment, DMSO had the highest (P < 0.05) Bax/Bcl-2 ratio; however, DNA fragmentation was similar (P > 0.05) among treatments after thawing. After in vitro culture, the percentage of normal follicles was similar (P > 0.05) between slow-freezing and vitrification methods; however, vitrification had greater (P < 0.05) stromal cell density than slow-freezing. In summary, equine ovarian tissue was successfully cryopreserved, increasing the viability of the cells in the ovarian tissue after thawing when using DMSO and EG for slow-freezing and vitrification methods, respectively. Therefore, these results are relevant for fertility preservation programs.

Ovarian fragment sizes affect viability and morphology of preantral follicles during storage at 4°C.

The method of transportation and the conditions imposed on the ovarian tissue are pivotal aspects for the success of ovarian tissue cryopreservation (OTC). The aim of this study was to evaluate the effect of the size of the ovarian tissue (e.g. whole ovary, biopsy size and transplant size) during different times of storage (0, 6, 12 and 24 h) on the structural integrity of equine ovarian tissue transported at 4°C. Eighteen pairs of ovaries from young mares (<10 years old) were harvested in a slaughterhouse and processed to simulate the fragment sizes (biopsy and transplant size groups) or kept intact (whole ovary group) and stored at 4°C for up to 24 h in α-MEM-enriched solution. The effect of the size of the ovarian tissue was observed on the morphology of preantral follicles, stromal cell density, DNA fragmentation and mitochondrial membrane potential. The results showed that (i) biopsy size fragments had more morphologically normal preantral follicles after 24 h of storage at 4°C; (ii) mitochondrial membrane potential was the lowest during each storage time when the whole ovary was used; (iii) DNA fragmentation rate in the ovarian cells of all sizes of fragments increased as storage was prolonged and (iv) transplant size fragments had increased stromal cell density during storage at cool temperature. In conclusion, the biopsy size fragment was the best to preserve follicle morphology for long storage (24 h); however, transportation/storage should be prior determined according to the distance (time of transportation) between patient and reproduction centers/clinics.

Effects of Cryoprotectant Agents on Equine Ovarian Biopsy Fragments in Preparation for Cryopreservation

The exposure effect of cryoprotectant agents (CPAs) on morphology of preantral follicles (PAFs), stromal cell and PAF densities, and area of equine ovarian fragments were evaluated. Three independent experiments with identical methodologies were performed. Each experiment was composed of one CPA (dimethyl sulfoxide, ethylene glycol, or propylene glycol) and was performed in three replicates. Ovarian biopsy fragments were harvested from six mares in each experiment and submitted to the cryoprotectants using four times of exposure (0, 10, 15, and 20 minutes). PAF and stromal cell densities, and area of the fragments were not affected (P > .05) by any of the CPAs throughout the time of exposure. However, the morphology of the PAFs was affected (P < .05) by the CPAs. In the propylene glycol and dimethyl sulfoxide, higher (P < .05) percentages of abnormal PAFs were observed at 10 and 20 minutes of exposure, respectively. The PAF morphology in the ethylene glycol treatments was not affected (P > .05) throughout the times of exposure. Positive correlations (r = 0.57–0.77; P < .001, power = 96%–99%) were identified between PAF density and stromal cell density in all experiments. In conclusion, (1) ethylene glycol seems to be a less harmful CPA to equine PAFs, (2) exposure to CPAs did not affect the cell density and area of ovarian fragments, (3) PAF density was positively correlated with stromal cell density, and (4) stromal cell density did not affect the morphology of PAFs.

44 EFFECT OF CRYOPROTECTANT AGENTS IN EQUINE OVARIAN BIOPSY FRAGMENTS

Studies on ovarian tissue preservation in horses are scarce, and only one research group (Devireddy et al. 2006 Mol. Reprod. Develop. 73, 330–341) has tested the effect of the cryoprotectant agents in equine ovarian tissue. The purpose of this study was to evaluate (1) the effect of cryoprotectant agents in the morphology of equine preantral follicles (PAF) and structure of the ovarian tissue, (2) the relationship between ovarian stromal cell density and PAF density, and (3) the association of ovarian stromal cell density with PAF morphology after exposure to cryoprotectant agents. Three independent experiments with identical methodologies were performed in this study. Each experiment was composed by one cryoprotectant agent (dimethyl sulfoxide, ethylene glycol, propylene glycol) performed in 3 replicates. Ovarian biopsy fragments (1.5 × 1.5 × 10 mm) were harvested from 6 mares and submitted to 4 times of exposure (0, 10, 15, 20 min) at room temperature in a solution of α-minimal essential medium (MEM)+ and one cryoprotectant (dimethyl sulfoxide, ethylene glycol, or propylene glycol) at a concentration of 1.5 M. The cryoprotectant removal was performed by a 3-step (5 min each) equilibration process using (1) α-MEM + 0.5 M sucrose, (2) α-MEM + 0.25 M sucrose, and (3) α-MEM alone after each time of exposure. All fragments were fixed in Bouin’s solution for histological analysis. Data were analysed by ANOVA, Fisher’s exact test, Spearman’s rank correlation, and power test. The PAF density, stromal cell density, and area of the fragments were not affected (P &gt; 0.05) by any of the cryoprotectant agents throughout the time of exposure. However, the morphology of the PAF was affected (P &lt; 0.05) by the cryoprotectant agents. In the propylene glycol and dimethyl sulfoxide, higher (P &lt; 0.05) percentages of abnormal PAF were observed at 10 and 20 min of exposure, respectively. However, the PAF morphology in the ethylene glycol treatments was not affected (P &gt; 0.05) throughout the times of exposure. Strong correlations (range, 0.57 to 0.77; power, 96 to 99%) were identified between PAF density and stromal cell density in all experiments. When stromal cells were classified into groups of density (i.e. low, 25.67–34.66; medium, 34.67–43.66; and high, 43.67–52.67 cells/2500 μm2), only the high stromal cell density was positively correlated (P &lt; 0.001) with the PAF density; however, no correlation between stromal cell density and PAF morphology was observed. In conclusion, (1) ethylene glycol seems to be a less harmful cryoprotectant agent to equine PAF, (2) exposure to cryoprotectant agents did not affect the cell density and area of ovarian fragments, (3) PAF density was positively correlated with stromal cell density, and (4) stromal cell density did not affect the morphology of PAF.

Efeito do tipo de fixador e tempo de fixação na morfologia de folículos pré-antrais ovarianos bovinos

There are no efficient fixatives for histological analyses of ovarian tissue that permit an appropriate morphological analysis of ovary and their cells. The correct processing of the tissue is essential to avoid misinterpretation between follicular degeneration due to the physiological process of follicular atresia with signs of degeneration signals due to poor tissue fixation. This study aimed to identify the best fixative and better fixation period for morphological analysis of the functional unit of the ovary: follicle. Ovaries (n = 5) from five adult cows were collected from local abattoirs. Each ovary was divided into 12 fragments and submitted to six different fixatives in two different times (12 and 24h). It was analyzed 150 follicles per treatment. The best results were obtained with Carnoy’ and Bouin’s fixatives which had higher (P &lt; 0.05) proportion of viable follicles after fixation for 12 or 24h (88 and 83% for Carnoy’s fixative vs. 79 e 73% for Bouin). It was concluded that Carnoy and Bouin fixatives are the best options to preserve for up to 24 h the morphology of preantral follicles in bovine ovaries.

Adding Ascorbic Acid to Vitrification and IVC Medium Influences Preantral Follicle Morphology, but Not Viability

In this study, we analysed the effect on morphology and viability of ovine primordial follicles, when ascorbic acid (AA) was added to vitrification and in vitro culture (IVC) media. For morphological analysis, ovarian tissue was vitrified using DMSO or ethylene glycol (EG), to which AA was added or omitted. After warming, the tissue was fixed for histology or 1-day cultured in the presence or absence of AA. Isolated primordial follicles from ovine ovarian tissue vitrified with DMSO or EG, both supplemented with AA were stained with trypan blue for viability analysis, or 5-day cultured with or without AA followed by a viability analysis. In this study, we report on the successful vitrification protocol developed for ovine ovarian tissue using EG. Vitrification using DMSO reduced the percentage of morphological normal primordial follicles, whereas addition of AA to the vitrification and culture media did enhance these results (p < 0.05). However, vitrification in a DMSO + AA medium followed by 5-day IVC resulted in a significant decrease in the follicular viability, independently of the presence of AA in the IVC medium.