• Clinical and Experimental Reproductive Medicine
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• v.32 no.2
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• pp.91-99
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• 2005

Objective: To define an appropriate vitrification condition of preantral follicle that yields high survival and to evaluate growth and ovulation rate of mouse follicles during in vitro culture after vitrification. Methods: Preantral follicles were isolated mechanically from mouse ovaries that were surgically recovered from mice aged 14 days. Retrieved preantral follicles were placed in EG (Ethylene Glycol) for 2, 5, 10 minutes and transferred to EFS-40 (40% EG, 18% Ficoll-70, 0.5 M sucrose) for 0.5, 1, 2 minutes. And then, preantral follicles were placed onto an EM grid and submerged immediately in liquid nitrogen. Thawing was carried out at room temperature. After defining the most appropriate vitrification condition that yields high survival, in vitro growth and ovulation rate of follicles were evaluated. Results: Appropriate vitrification condition that yield high survival rate ($83.2{\pm}2.1%$) of preantral follicle was EG for 5 minutes and EFS-40 for 0.5 minutes. In vitro survival rate of the vitrified preantral follicles were $85.5{\pm}0.5%$, $67.9{\pm}0.8%$ and $40.2{\pm}0.5%$ on day 2, 6 and 10. And in vitro growth of the vitrified preantral follicles were $107.1{\pm}16.1{\mu}m$, $117.1{\pm}18.4{\mu}m$, $178.4{\pm}45.6{\mu}m$ and $325.4{\pm}54.4{\mu}m$ on day 0, 2, 6 and 10. Although in vitro survival rate and growth of vitrified preantral follicles were lower than that of non-vitrified preantral follicles, the patterns of survival and growth were similar in vitrified and non-vitrified preantral follicles. The ovulation rate of antral follicles that was grown from vitrified preantral follicles was $32.6{\pm}1.2%$. Conclusion: Vitrified preantral follicles could be grown to antral sizes, and mature oocytes that can be used for IVF-ET programs were produced successfully. These data suggest that cryopreservation of preantral follicle by vitrification can be used for the preservation of the fertility.

• Korean Journal of Animal Reproduction
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• v.24 no.4
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• pp.347-356
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• 2000

포유동물의 난소 내에는 많은 수의 primordial follicles 과 preantral follicles 이 존재하고 있으며, 이것은 수정란을 체외생산하기 위한 잠재적인 난자의 공급원이 될 수 있다. 생쥐 preantral follicles 내에 존재하는 난자의 체외성장과 발달을 위하여 몇몇 배양체계가 개발이 되었으며, 적당한 배양조건에서 감수분열 능력이 없는 preantral follicles 내의 난자가 체외배양을 통하여 난자 직경이 증가하고 완전한 핵성숙을 하는 것으로 나타났다. 또한, 체외성장 및 성숙된 난자로부터 생쥐 산자의 성공적인 생산은 preantral follicles 내의 난자가 체외배양을 통해서도 완전한 발달능력을 얻을 수 있음을 입증하였다. 그렇지만, 생쥐 preantral follicle로부터 수정란의 체외생산능력은 매우 낮은 것으로 보고되고 있다. 한편 사람을 비롯한 돼지, 소와 같은 중ㆍ대가축의 경우에는 pre antral follicle의 체외배양을 통하여 감수분열능이 있는 단계의 난자로까지의 발달이 아직 보고가 되지 않고 있다. 따라서 지금까지의 연구결과들을 종합해 볼 때, preantral follicles의 체외배양조건을 개선하거나 새로운 배양체계를 개발에 대한 많은 연구가 요구되고 있다. 사람과 중ㆍ대가축의 preantral follicles의 체외배양체계의 확립은 우수한 형질을 가진 동물의 확장, 희귀동물 혹은 멸종위기 동물의 보존에 이용될 수 있을 것이며, 그리고 암치료를 위하여 화학적, 방사선 치료를 받아야 하는 여성에게서 향후에 불입치료를 위한 방법으로 활용될 수 있을 것으로 기대된다.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.1
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• pp.35-39
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• 2019

This study aimed to recover the ovarian function through in vitro culture of preantral follicles from aged mice. First, we isolated the preantral follicles from ovaries of sixty-seven-week old B6D2F1 mice with decreased fecundity to know how many follicles were present in them, which was 6 preantral follicles including 2 primary, 2 early secondary and late secondary follicles from 8 aged mice. It was confirmed that a few follicles (~2) were present in aged mice through histological analysis compared to adult mice as control. The 9 days of in vitro culture of preantal follicles showed in vitro growth and induced maturation after treatment with hCG (2.5 IU/mL) and EGF (5 ng/mL). Cumulus cells in the cumulus-oocyte complexes (COCs) were removed using hyaluronidase and oocytes at the germinal vesicle (GV) and GV breakdown (GVBD) were obtained from preantral follicle culture of aged mice in vitro. In conclusion, these observations demonstrated that there still were a few preantral follicles in the ovaries of 67 week-old mice, which we were able to culture in vitro and oocytes were obtained from them. This study proposed an in vitro culture system using preantral follicle as a therapeutic strategy for fertility preservation in humans for assisted reproductive medicine.

• Proceedings of the KSAR Conference
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• 2000.10a
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• pp.9-9
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• 2000

The mammalian ovary has a large number of primordial and preantral follicles, which are a potential source of oocytes for the in vitro mass production of embryos. Several in vitro culture systems have been developed to support the growth and development of oocytes from mouse preantral follicles. Under the appropriate condition, meiotically incompetent oocytes from preantral follicles can grow to final size and complete nuclear maturation in vitro. Furthermore, the successful production of live young from in vitro grown and matured oocytes demonstrates that oocytes from preantral follicles are able to acquire full developmental capacity in vitro. However, the efficiency of in vitro production of embryos from mouse preantral follicles is still low. In farm animals as well as human, the growth of oocyte from preantral follicle to the meiotic competence stage has yet to be demonstrate. Therefore, further studies to improve the culture condition or to develope new culture system should be needed in the future. In addition, the visible progress in the establishment of the in vitro culture system for preantral follicles of farm animals and human could help to enlarge the populations of valuable agricultural, phamaceutical product-producing, and endangered animals, and to rescue the oocytes of women about to undergo clinical procedures that jeopardize oocytes.

• Reproductive and Developmental Biology
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• v.32 no.2
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• pp.111-115
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• 2008

The aim of this study was to examine more effective cryoprotectant for the cryopreservation of mouse preantral follicles. Enzymetically isolated preantral follicles from 12-day-old mice were cryopreserved by a slow freezing protocol with 1.5 M propanediol (PROH), dimethyl sulphoxide (DMSO) or glycerol (GLY) and then grown and matured in vitro for 11 days after thawing. The survival of preantral follicles immediately after freezing and thawing was not different among the PROH (68.2%), DMSO (72.4%) and GLY (72.1%). After grown and matured in vitro, the rates of survival and metaphase II oocytes were 54.9% and 36.6% for PROH which was significantly higher rates (p<0.05) compared with the rates obtained from DMSO (16.9% and 9.0%) and GLY (16.3% and 7.5%). The diameter of metaphase II oocytes from pre antral follicles frozen in PROH ($67.4{\pm}1.8\;{\mu}m$) was significantly (p<0.05) smaller than that of the fresh preantral follicles ($69.1{\pm}2.3\;{\mu}m$). The results from the present study revealed that PROH is more suitable cryoprotectant for the cryopreservation of mouse preantral follicles.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.2
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• pp.117-122
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• 2019

The objective of this study was to establish an in vitro culture system for ovarian preantral follicles of B6D2F1. First, we optimized the in vitro preantral-follicle culture by culture duration, follicle stimulating hormone (FSH) type, and activin A concentration. Duration of in vitro culture for 9, 11, and 13 days was sufficient for the normal development of preantral follicles to antral follicles. Formation of cumulus cell-oocyte complex (COC) was induced by treatment with human chorionic gonadotropin (hCG; 2.5 IU/mL) and epidermal growth factor (EGF; 5 ng/mL). In addition, metaphase II (MII) oocytes formed during this in vitro culture of preantral follicles. In vitro preantralfollicle culture for 9 days showed higher rates of growth and maturation, thus yielding a greater number of antral follicles, and there were significant differences (p < 0.05) in the number of MII oocytes (that formed from these preantral follicles via differentiation) between the 9-day culture and 11-day or 13-day culture. The follicles cultured for 9 days contained a tightly packed well-defined COC, whereas in follicles cultured for 11 days, the COC was not well defined (spreading was observed in the culture dish); the follicles cultured for 13 days disintegrated and released the oocyte. Second, we compared the growth of the preantral follicles in vitro in the presence of various FSH types. There were no significant differences in the growth and maturation rates and in differentiation into MII oocytes during in vitro culture between preantral follicles supplemented with FSH from Merck and those supplemented with FSH from Sigma. To increase the efficiency of MII oocyte formation, the preantral follicles were cultured at different activin A concentrations (0 to 200 ng/mL). The control follicles, which were not treated with activin A, showed the highest rate of differentiation into antral follicles and into MII oocytes among all the groups (0 to 200 ng/mL). Therefore, activin A (50 to 200 ng/mL) had a negative effect on oocyte maturation. Thus, in this study, we propose an in vitro system of preantral-follicle culture that can serve as a therapeutic strategy for fertility preservation of human oocytes for assisted reproductive medicine, for conservation of endangered species, and for creation of superior breeds.

• Clinical and Experimental Reproductive Medicine
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• v.48 no.4
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• pp.347-351
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• 2021

Objective: We investigated the impact of vitamin D₃ (VD3) supplementation during mouse preantral follicle culture in vitro and the mRNA expression of 25-hydroxylase (CYP2R1), 1-alpha-hydroxylase (CYP27B1), and vitamin D receptor (VDR) in mouse ovarian follicles at different stages. Methods: Preantral follicles were retrieved from 39 BDF1 mice (7-8 weeks old) and then cultured in vitro for 12 days under VD3 supplementation (0, 25, and 50 pg/mL). Follicular development and the final oocyte acquisition were assessed. Preantral follicles were retrieved from 15 other BDF1 mice (7-8 weeks old) and cultured without VD3 supplementation. Three stages of mouse ovarian follicles were obtained (preantral, antral, and ruptured follicles). Total RNA was extracted from the pooled cells (from 20 follicles at each stage), and then reverse transcriptase-polymerase chain reaction was performed to identify mRNA for CYP2R1, CYP27B1, and VDR. Results: The survival of preantral follicles, rates of antrum formation and ruptured follicles (per initiated follicle) and the number of total or mature oocytes were all comparable among the three groups. Both CYP2R1 and CYP27B1 were expressed in antral and ruptured follicles, but not in preantral follicles. VDR was expressed in all three follicular stages. Conclusion: VD3 supplementation in vitro (25 or 50 pg/mL) did not enhance mouse follicular development or final oocyte acquisition. Follicular stage-specific expression of CYP2R1, CYP27B1, and VDR was observed.

• Reproductive and Developmental Biology
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• v.37 no.4
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• pp.193-197
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• 2013

In order to investigate the effects of antioxidants on the culture of mouse preantral follicles in vitro, we examined the effects of taurine, glutathione and catalase on their growth and maturation. Addition of taurine was not effective on the survival of preantral follicles. However, metaphase II rates of oocytes within preantral follicles were significantly higher in 1 mM treated group than in control and 10 mM treated group (p<0.05). Glutathione did not improved the rates of survival and metaphase II oocytes. However, metaphase II rates of oocytes progressively decreased with increasing glutathione concentration. Catalase also showed that the rates of survival and metaphase II oocytes progressively decreased with increasing concentration. Especially, all of preantral follicles cultured in medium containing 100 IU/ml catalase were degenerated. These results suggest that low concentraion of taurine, as an antioxidant, have positive effect on the culture of mouse preantral follicles in vitro.

• Journal of Embryo Transfer
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• v.26 no.4
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• pp.223-227
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• 2011

The objective of this study was to compare of different isolation method of mouse preantral follicles, and to examine in vitro development of mouse preantral follicles isolated by different method. Preantral follicles were mechanically or enzymatically extracted from mouse ovaries. Mechanical isolation method used fine gauge needles and enzymatic method of isolating follicles used collagenase. The recovered preantral follicles were cultured for 10 days in alpha-minimal essential medium (${\alpha}$-MEM) + 5% FBS + Insulin-Transferrin-Selenium (ITS) + 100 mIU/ml FSH. The collected primary follicles by enzymatic treatment were higher than mechanical method. Others stage preantral follicle by mechanical isolation were higher than enzymatic method. After 10 days of culture, no statistical differences were shown in survival rates of preantral follicle among the 2 culture groups. The metaphase II rates of the oocytes were significantly higher (p<0.05) in mechanical method (17.8%) than in enzymatic method (5.1%). These results suggest that the isolation method of choice depends on the target stage preantral follicles and mechanical isolation is an optimal method of preantral folliclesin a culture of mouse preantral follicle.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.12
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• pp.1711-1715
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• 2006

To predict the number of preantral (primordial, primary and secondary) follicles retrieved from bovine ovaries, we examined the relationship between morphological parameters of ovaries and number of preantral follicles retrieved mechanically. The preantral follicles were retrieved mechanically by slicing ovarian tissue and the influences of size of the ovaries, number of antral follicles, and presence of cystic follicle and corpus luteum on the retrieval were evaluated. Total 77 ovaries were used and significant (p<0.05) relationship was detected between the number of antral follicles and the presence of cystic follicles, and the retrieval number. More preantral follicles were retrieved from the ovaries having more than 20 antral follicles than those having less than 20 antral follicles (17,760${\pm}$5,637 vs. 3,689${\pm}$537) in the ovarian cortex. The retrieval number was significantly reduced in cystic ovaries compared with non-cystic ovaries (5,167${\pm}$825 vs. 20,631${\pm}$6,507). However, neither ovary size (<3.5, 3.5 to 4.0, 4.0 to 4.5 and >4.5 cm) nor the presence of corpus luteum affected the follicle retrieval. In conclusion, the number of preantral follicles retrieved from the ovaries can simply be predicted by the number of antral follicles and the presence of cystic follicles in the ovarian cortex.