Recovery of large preantral follicles from buffalo ovary: Effect of season and corpus luteum

Effect of retinol as antioxidant on the post-thaw viability and the expression of apoptosis and developmental competence-related genes of vitrified preantral follicles in buffalo (Bubalus bubalis)

The present study evaluated the effect of supplementation of retinol in the vitrification solution on the viability, apoptosis and development-related gene expression in vitrified buffalo preantral follicles. Preantral follicles isolated from cortical slices of ovaries were randomly assigned into three groups: Group1-Control fresh preantral follicles; Group 2-Vitrification treatment (Vitrification solution 1 (VS1) -TCM-199 + 25 mM HEPES + Foetal bovine serum (FBS) 10%, Ethylene glycol (EG): 10%, Dimethyl sulphoxide (DMSO): 10%, Sucrose-0.3 M for 4 min; VS2- TCM-199 + 25 mM HEPES + FBS10%, EG:25%, DMSO: 25%, Sucrose:0.3 M for 45 s); Group3-vitrification treatment +5 μM of Retinol. Preantral follicles were placed in corresponding vitrification medium and plunged into liquid nitrogen (-196°C). After a week, the follicles were thawed and analysed for follicular viability and gene expression. There was no significant difference in the viability rates among the Group 1(Fresh preantral follicles) (91.46 ± 2.39%), Group 2 (89.59 ± 2.46%) and Group 3 (87.19 ± 4.05%). There was a significantly (p < .05) higher mRNA expression of BCL2L1, GDF-9 and BMP-15 in the vitrification + retinol group compared with the control group. There was a significantly (p < .05) higher expression of Caspase-3 and Annexin-5 in the vitrification group and Vitrification + retinol group compared with control group of follicles. It is concluded that the supplementation of 5 μM of Retinol in Vitrification solution was an efficient vitrification procedure for the vitrification of buffalo preantral follicles.

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.

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.

The Mare Model to Study the Effects of Ovarian Dynamics on Preantral Follicle Features

Ovarian tissue collected by biopsy procedures allows the performance of many studies with clinical applications in the field of female fertility preservation. The aim of the present study was to investigate the influence of reproductive phase (anestrous vs. diestrous) and ovarian structures (antral follicles and corpus luteum) on the quality, class distribution, number, and density of preantral follicles, and stromal cell density. Ovarian fragments were harvested by biopsy pick-up procedures from mares and submitted to histological analysis. The mean preantral follicle and ovarian stromal cell densities were greater in the diestrous phase and a positive correlation of stromal cell density with the number and density of preantral follicles was observed. The mean area (mm²) of ovarian structures increased in the diestrous phase and had positive correlations with number of preantral follicles, follicle density, and stromal cell density. Biopsy fragments collected from ovaries containing an active corpus luteum had a higher follicle density, stromal cell density, and proportion of normal preantral follicles. In conclusion, our results showed: (1) the diestrous phase influenced positively the preantral follicle quality, class distribution, and follicle and stromal cell densities; (2) the area of ovarian structures was positively correlated with the follicle and stromal cell densities; and (3) the presence of an active corpus luteum had a positive effect on the quality of preantral follicles, and follicle and stromal densities. Therefore, herein we demonstrate that the presence of key ovarian structures favors the harvest of ovarian fragments containing an appropriate number of healthy preantral follicles.

Amburana cearensis leaf extract maintains survival and promotes in vitro development of ovine secondary follicles

The antioxidant properties of Amburana cearensis extract may be a useful substitute for standard cell culture medium. Thus, the aim of this study was to evaluate the effect of this extract, with or without supplementation, on in vitro survival and development of sheep isolated secondary follicles. After collection of the ovaries, secondary follicles were isolated and cultured for 18 days in α-MEM+ supplemented with bovine serum albumin, insulin, transferrin, selenium, glutamine, hypoxanthine and ascorbic acid (control medium) or into medium composed of different concentrations of A. cearensis extract without supplements (Amb 0.1; 0.2 or 0.4 mg/ml) or A. cearensis extract supplemented with the same substances described above for α-MEM+ supplementation. The A. cearensis supplemented medium was named Amb 0.1+; 0.2+ or 0.4+ mg/ml. There were more morphologically normal follicles in Amb 0.1 or Amb 0.4 mg/ml than in the control medium (α-MEM+) after 18 days of culture. Moreover, the percentage of antrum formation was significantly higher in Amb 0.1 or Amb 0.2 mg/ml than in α-MEM+ and Amb 0.1+ mg/ml, and similar to the other treatments. All A. cearensis extract media induced a progressive and significant increase in follicular diameter throughout the culture period. In conclusion, this study showed that 0.1 mg/ml of this extract, without supplementation, maintains follicular survival and promotes the development of ovine isolated secondary follicles in vitro. This extract can be an alternative culture medium for preantral follicle development.

Isolation and culture of preantral follicles for retrieving oocytes for the embryo production: present status in domestic animals

The development of efficient ovarian preantral follicle (PF) isolation and culture systems provide a large number of oocytes for the manipulation and embryo production. It also helps for understanding the mechanisms of follicle and oocyte development. Isolation and culture protocols for PFs were developed for many domestic species like cattle, buffalo, sheep, goat, pig, horse, camel, dog and cats; however, embryo production from oocytes derived from in vitro grown PFs was reported only in pigs, buffalo, sheep and goat. The rate of oocyte maturation from PFs grown in vitro is low and requires considerable research. This paper presents an overview of isolation and culture systems of PFs that have been developed for domestic species (cattle, buffalo, sheep, goat, pigs, horse, camel, dog and cat) along with the current status of progress achieved in the direction of producing embryos using PFs as the source of oocyte in these species.

Cryopreservation and in vitro culture of caprine preantral follicles

Preantral follicles (PFs) form a far larger oocyte reservoir (~90% of the follicular population) than antral follicles. Several laboratories have focussed efforts on cryopreservation and in vitro culture (IVC) of PFs to obtain large numbers of fertilisable oocytes. This technology could be used to improve the reproductive potential of economically important animals, including goats, to preserve endangered species and breeds and improve fertility after chemotherapy in young women. Caprine PFs have been successfully cryopreserved using either vitrification or slow freezing. In addition, in vitro embryo production from oocytes enclosed in caprine PFs grown and matured in vitro was also achieved. The present paper selectively reviews the published studies on cryopreservation and IVC of caprine PFs to highlight advances, limitations and prospects.

Effects of IGF-1, TGF-alpha plus TGF-beta1 and bFGF on in vitro survival, growth and apoptosis in FSH-stimulated buffalo (Bubalis bubalus) preantral follicles

OBJECTIVE

Investigate the effect of various growth factors viz. IGF-I, TGF-alpha + TGF-beta1 and bFGF either alone or in combination, with FSH on in vitro growth, survival, antrum formation, steroidogenesis and apoptosis of buffalo preantral follicles (PFs).

METHODS

Buffalo ovaries were collected from abattoir; PFs were isolated and divided into five treatment groups. TCM-199 supplemented with 10% FBS, 1% ITS+EGF+FSH control (group a), control+IGF-I (group b), control + TGF-alpha + TGF-beta1 (group c), control + IGF-I + TGF-alpha + TGF-beta1 (group d) and control+bFGF (group e). Progesterone (P4) and 17beta-estradiol (E2) concentrations were evaluated by RIA and apoptosis by TUNEL assay.

RESULTS

TGF-alpha + TGF-beta1 inhibited follicular survival and induced oocyte apoptosis, while IGF-I + TGF-alpha + TGF-beta1 suppressed this inhibitory action. IGF-I significantly (P < 0.05) enhanced the follicle survival, growth and induced antrum formation. FGF had greater effects on both survival and growth rate of oocytes than other treatment groups. Progesterone and estradiol accumulation was significantly (P < 0.05) greater in presence of FGF and IGF-I than TGF-alpha + TGF-beta1.

CONCLUSION

Survival, growth, antrum formation and steroidogenesis are stimulated by IGF-I and bFGF, whereas TGF-alpha + TGF-beta1 inhibited growth and survival of PFs which led to induced oocyte apoptosis in buffalo PFs.

Viability and growth of buffalo preantral follicles and their corresponding oocytes in vitro: effect of growth factors and beta mercaptoethanol

The present study was undertaken to isolate buffalo preantral follicles (PFs), to test the viability and sizes of buffalo PFs and to examine the effect of various growth factors (insulin-like growth factor, fibroblast growth factor) and an antioxidant (beta mercaptoethanol) on the in vitro growth, survival and antrum formation rates of buffalo PFs and growth rates of oocytes in cultured PFs. Preantral follicles from slaughtered buffalo ovaries were recovered by a combined mechanical and enzymatic method. The recovery rates of >40-100, 101-200, 201-300, 301-400 and 401-500 microm PFs were 5.1, 3.2, 3.1, 6.3 and 5.1 per ovary, respectively. The corresponding viability rates were 76.1%, 78.1%, 85.2%, 92.5% and 92.6%, respectively. There was a positive correlation (r = 0.73) between oocyte size and the follicular size. However, there was no significant correlation between the size of oocyte and its viability at the time of its retrieval from ovary. Insulin-like growth factor and fibroblast growth factor improved the survival of buffalo PFs and regulated their growth in culture. The growth factors and beta mercaptoethanol in association synergically improved the growth and survival of buffalo PFs.

Survival and developmental competence of buffalo preantral follicles using three-dimensional collagen gel culture system

The aim of the present study was to develop a three-dimensional (3D) collagen gel culture system for the in vitro growth and survival of buffalo preantral follicles with or without growth factors. Buffalo ovaries were collected from a local abattoir and preantral follicles were isolated through microdissection. Isolated preantral follicles were put either in collagen gel coated culture dish or embedded in a microdrop of collagen gel. The culture medium was TCM-199 fortified with fetal calf serum (10%), insulin transferin selenium solution (ITS, 1%), epidermal growth factor (EGF, 20 ng/ml) and follicle stimulating hormone (FSH, 0.5 microg/ml). Follicles were divided into three groups and cultured in the medium described above (group a, control), with addition of insulin like growth factor (IGF-I, 100 ng/ml, group b), or with addition of IGF-I and basic fibroblast growth factor (bFGF, 10 ng/ml, group c). Preantral follicles were incubated at 38.5 degrees C in 5% CO(2) and maximum humidity. Culture medium was replenished after every 72 h and spent medium was stored at -30 degrees C for hormone analysis. We found that the extracellular matrix of collagen gel maintained follicle viability and growth by providing surface interaction and increasing attachment of follicles. Preantral follicles embedded in collagen gel droplets had better antrum formation and development as compared to the whole surface coated culture method. Follicles cultured with IGF-I on collagen gel matrix showed a significantly (P<0.05) higher survival rate and larger mean diameter of follicles on day 10 of culture with improved growth and mucification as compared to the control group. However, follicles cultured in the combination of IGF-I with bFGF had decreased survival rate and smaller mean follicles diameter than the IGF-I group (b). Progesterone (P(4)) accumulation was greater on day 9 of culture in follicles cultured in IGF-I as compared to control; whereas, P(4) was markedly decreased in the combination of IGF-I with bFGF. Follicles of the control group could survive for up to 10-15 days before degenerating, but follicles cultured with growth factors were able to survive up to 20 days and showed signs of early antrum formation. In summary, we have shown that collagen gel was a novel and efficacious 3D microenvironment for the extended culture of buffalo preantral follicles. Supplementation of culture medium with growth factors was found to be essential for antrum formation.

Production of buffalo embryos using oocytes from in vitro grown preantral follicles

The present study examines the use of buffalo preantral follicles as a source of oocytes for in vitro embryo production. Preantral follicles were isolated from abattoir-derived buffalo ovaries and were grown for 100 days in five different culture systems: (1) minimum essential medium (MEM); (2) coconut water; (3) MEM + ovarian mesenchymal cell (OMC) co-culture; (4) MEM + granulosa cell (GC) co-culture; or (5) MEM + cumulus cell (CC) co-culture. Low growth rates for the preantral follicles were observed when follicles were cultured in MEM or coconut water medium. Moderate growth rates were seen for OMC and GC co-cultures, and high rates of growth were observed when follicles were grown in CC co-culture. The survival of preantral follicles was low in the MEM culture (<25%), but was over 75% in the other culture systems. Oocytes were not recovered from the MEM group, while an oocyte recovery rate of 80-100% was observed when the follicles were cultured with coconut water/somatic cells. Transferable embryos could be produced only with the oocytes obtained from preantral follicles grown in the OMC and CC co-culture systems. This study demonstrates, for the first time, that it is possible to produce buffalo embryos by in vitro fertilization of oocytes derived from in vitro grown preantral follicles.

Co-culture of buffalo preantral follicles with different somatic cells

The effect of co-culture of buffalo preantral follicles (PFs) with different somatic cells, i.e, cumulus, granulosa, ovarian mesenchymal and oviductal epithelial cells was studied. Large PFs (250-450 microm) were isolated by microdissecting the trypsin (1%) digested ovarian cortical slices. Cumulus cells were isolated by repeated pipetting of oocytes, granulosa cells were isolated by aspirating from punctured PFs and ovarian mesenchymal cells were isolated from ovarian cortex by scraping the cortical slices and passing through 20 microm filter. Preantral follicles were cultured in standard culture medium without somatic cells or co-cultured with cumulus cells, granulosa cells, ovarian mesenchymal cells and oviductal epithelial cells for 80 days. The growth rate (microm/day) of the PFs was monitored by measuring follicular diameter on day 0, 30, 60 and 80 days of culture. The viability of PFs was evaluated by trypan blue staining. The results indicated that PFs co-cultured with cumulus, granulosa and ovarian mesenchymal cells had a better development and survivality compared with control and those co-culture with oviductal epithelial cells. Maximum growth and survivality of PFs were achieved when cultured with cumulus cells. It is concluded that inclusion of somatic cells in PF culture media had beneficial effect on the growth of PFs and cumulus cells supported maximum growth and survivality of PFs in vitro of all somatic cells tested.