• Clinical and Experimental Reproductive Medicine
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• v.46 no.2
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• pp.43-49
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• 2019

Primordial follicle activation is a process in which individual primordial follicles leave their dormant state and enter a growth phase. While existing hormone stimulation strategies targeted the growing follicles, the remaining dormant primordial follicles were ruled out from clinical use. Recently, in vitro activation (IVA), which is a method for controlling primordial follicle activation, has provided an innovative technology for primary ovarian insufficiency (POI) patients. IVA was developed based on Hippo signaling and phosphatase and tensin homolog (PTEN)/phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/forkhead box O3 (FOXO3) signaling modulation. With this method, dormant primordial follicles are activated to enter growth phase and developed into competent oocytes. IVA has been successfully applied in POI patients who only have a few remaining remnant primordial follicles in the ovary, and healthy pregnancies and deliveries have been reported. IVA may also provide a promising option for fertility preservation in cancer patients and prepubertal girls whose fertility preservation choices are limited to tissue cryopreservation. Here, we review the basic mechanisms, translational studies, and current clinical results for IVA. Limitations and further study requirements that could potentially optimize IVA for future use will also be discussed.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.75-75
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• 2003

Transition of the resting primordial follicle to the growing primary follicle is a critical process for female reproduction, but its mechanism is poorly understood. The present study was conducted to investigate gene expression profile at the primordial-primary follicle transition process. We isolated total RNA of female mouse ovary at day1 (contains only primordial follicles) and day5 (contains primordial and primary follicles) and synthesized cDNA using annealing control primers (ACP; Seegene, Inc., Seoul, Korea). ACP provides annealing specificity and sensitivity to the template and allows to identify only authentic differentially expressed genes (DEGs). We used total 80 ACPs for PCR, observed PCR products on 2% agarose gel, cloned 42 DEGs using TOPO TA cloning vector, sequenced, and analyzed by BLAST search. Sequences of 34 clones significantly matched database entries while 4 clones were novel and 4 clones were EST. Two of 34 genes were specifically expressed only in day 5 ovaries (Sui1-rs1, Apg3p/Aut1p-like), and rest of 32 genes were expressed in both stages but were differential in amount. Differential expression was confirmed using semiquantitative RT-PCR, and there was no false positive. Anx11 and Pepp2-pending were highly expressed genes in day1-, while BPOZ, Ches1, Kcmf1, NHE3, Nid2, Ninj1, SENP3 and Survivin were highly expressed genes in day5-ovary. List of genes would provide insight for further study of mechanism regulating primordial-primary follicle transition.

• Nuclear Engineering and Technology
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• v.31 no.4
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• pp.385-390
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• 1999

Ovarian follicles are faced with one of two fates, atresia or development. Up to 99% of follicles become degenerated rather than ovulated in female life span. Thus, atresia occurs at all stages of follicle development in mammalian ovaries. In the present experiment, the effect of ${\gamma}$-radiation on primordial follicles was morphologically analyzed in a mouse ovary. Thirty-seven percent of the primordial follicles in the non-irradiated control mice ovaries were abnormal. At day 8 post irradiation, most of primordial follicles became atretic. They lost their integrity of architecture in the follicular shape. Then, all the oocytes disappeared from the follicles. And only 3 to 4 granulosa cells lay down onto the basement membrane. Disappearance of granulosa cells or oocytes resulted from the radiation-induced apoptotic process. It is definitely clear that ${\gamma}$-radiation induces rapid apoptotic degeneration of the primordial follicles. The morphological degeneration induced by radiation in the primordial follicles can be used as an experimental model to draw out a deeper insight for radioprotectant researches.

• Clinical and Experimental Reproductive Medicine
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• v.39 no.1
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• pp.10-14
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• 2012

The ovarian follicles develop initially from primordial follicles. The majority of ovarian primordial follicles are maintained quiescently as a reserve for the reproductive life span. Only a few of them are activated and develop to an advanced follicular stage. The maintenance of dormancy and activation of primordial follicles are controlled by coordinated actions of a suppressor/activator with close communications with somatic cells and intra-oocyte signaling pathways. Many growth factors and signaling pathways have been identified and the transforming growth factor-beta superfamily plays important roles in early folliculogenesis. However, the mechanism of maintaining the dormancy and survival of primordial follicles has remained unknown for decades. Recently, since the first finding that all primordial follicles are activated prematurely in mice deficient forkhead box O3a, phosphatidylinositol 3 kinase/phosphatase and tensin homolog (PTEN) signaling pathway was reported to be important in the regulation of dormancy and initial follicular activation. With these informations on early folliculogenesis, clinical application can be expected such as in vitro maturation of immature oocytes or in vitro activation of follicles by PTEN inhibitor in cryopreserved ovarian cortical tissues for fertility preservation.

• Development and Reproduction
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• v.4 no.2
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• pp.137-145
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• 2000

The regulatory mechanisms of the initiation and the formation of ovarian follicles during fetal stage of mammals are largely unknown. In addition to the gonadotropins secreted from pituitary, various growth factors, and steroid hormones are believed to be involved in the differentiation and initiation of growth of primordial follicles consisting of primordial germ cells migrated from yolk sac and streamed cells from mesonephric somatic cells. In human, primordial follicles that have already initiated differentiation at fetal stage undergo either folliculogenesis to ovulate or atresia after growth. Some of primordial follicles remain without growth for 50 years or longer. The objective of this paper is to review the mechanism of the formation, growth arrest, and initiation of primordial follicles in human fetal and neonatal ovaries.

• Development and Reproduction
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• v.6 no.2
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• pp.89-96
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• 2002

The present study was conducted to elucidate genes involved in the primordial-primary follicular transition. By using suppression subtractive hybridization, day1- and day5-subtracted cDNA libraries were obtained with the forward and reverse subtraction method, respectively. In toto, 357 clones were sequenced and analyzed by BLAST and RIKEN program. Sequences of 330 clones significantly matched database entries while 27 clones were novel. Forty-two and 47 genes with known functions were different between day1 and day5 ovaries. Four genes, GDF8, lats2, septin2, and wee1, from the day1 subtracted cDNA library, and 6 genes, HSP84, laminin2, MATER, MTi7, PTP, and wrn, from day5-subtracted cDNA library were chosen, and their differential expression was evaluated using RNAs from whole ovaries as well as captured primordial and primary follicles by laser captured microdissection. Results from the present study would provide insight for the future study on the mechanisms involved in primordial-primary follicle transition in the mouse in addition to the human ovary.

• Journal of Animal Reproduction and Biotechnology
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• v.36 no.1
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• pp.51-58
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• 2021

Kisspeptin, a neuropeptide and the master controller of reproductive axis upstream to GnRH neurons, and its receptor are also expressed in extra-hypothalamic tissues, such as ovaries. As systemic kisspeptin has been shown to modulate follicular dynamics in cattle, we hypothesized that kisspeptin has direct actions on the ovarian follicular development. We also hypothesized that kisspeptin regulation of primordial follicle development is via modulation of VEGF expression. In order to test these hypotheses, we cultured caprine ovarian cortical strips in vitro for 7 days with supplementation of kisspeptin at 1, 10 and 100 µM concentration and observed the development of primordial follicles into intermediate, primary and secondary follicles. We also studied the alteration in the expression profile of VEGF and VEGF transcript variant 2 mRNA during follicular development in the presence of kisspeptin. We confirmed the presence of GPR54 in goat ovaries in our preliminary studies. Supplementation of kisspeptin at 1 and 10 µM concentration facilitated the development of primordial follicles into intermediate, primary and secondary follicles with less number of degenerated follicles while the same at 100 µM resulted in degeneration of follicles. We observed a drastic increase in the expression profile of VEGF and VEGF transcript variant 2 mRNA upon culture which was independent of kisspeptin treatment. In conclusion, our studies show that kisspeptin facilitates ovarian primordial development in vitro.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.2
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• pp.93-100
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• 2022

Objective: The impact of imatinib, a tyrosine kinase inhibitor, on ovarian follicles and several proteins related to follicular function and apoptosis was investigated in mice. Methods: Saline, cyclophosphamide (Cp; 50 or 75 mg/kg), or imatinib (7.5 or 15 mg/kg) was injected once intraperitoneally into female B6D2F1 mice (18 mice in each group). In multiple ovarian sections, the number of various types of follicles and the proportion of good-quality (G1) follicles were counted. The levels of six proteins (anti-Müllerian hormone [AMH], BCL-xL, BAX, acid sphingomyelinase [A-SMase], caspase-3, and α-smooth muscle actin [α-SMA]) within the whole ovaries were quantified using Western blots. Results: Compared to the saline group, a significant reduction of the primordial follicle count was observed in the group treated with imatinib 7.5 and 15 mg/kg, as well as in the group treated with Cp 75 mg/kg. Administration of Cp significantly decreased the proportion of G1 primordial follicles, but administration of imatinib did not. No differences in the AMH, anti-apoptotic BCLX-L, pro-apoptotic BAX, and A-SMase levels in the ovarian tissues were observed among the five groups. However, caspase-3 and α-SMA levels were significantly higher in the imatinib and Cp groups than in the saline group. Conclusion: The administration of imatinib to mice significantly reduced the primordial follicle count and increased the protein levels of caspase-3 and α-SMA. Our findings suggest that imatinib potentially exerts ovarian toxicity via apoptotic processes, similarly to Cp.

• Development and Reproduction
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• v.7 no.2
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• pp.127-136
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• 2003

The present study was conducted to investigate gene expression profile of mouse ovaries during the primordial-primary follicle transition. We isolated total RNA from mouse ovaries at day1(contains only primordial follicles) and day5(contains both primordial and primary follicles) and synthesized cDNA using annealing control primers(ACP, Seegene, Inc., Seoul, Korea). Using 80 different ACPs for PCR, we cloned, sequenced, and analyzed identities of 41 differentially expressed genes(DEGs). According to BLAST analysis, sequences of 33 clones significantly matched database entries, 4 clones were novel, and 4 clones were ESTs. We selected 8 DEGs with interesting functions, Anx11 and Pepp2-Pending highly expressed in day1 ovary, while Apg3/Autlp-like, BPOZ, Ches1, Kcmf1, NHE3, Nid2, Ninj1, SENP3, Suil-rsl, and TIAP/m-survivin highly expressed in days ovary, and confirmed their different expression between day1 ovaries and days ovaries using semi-quantitative RT-PCR. There was no false positive result. Using in situ hybridization, we found that almost all of genes studied were expressed in the oocyte from primordial follicle stage but expression decreased from primary follicle stage. Meanwhile their expression was increased in cuboidal granulosa cells. Different expression of BPOZ and TIAP/m-survivin between primordial and primary follicles was confirmed by using laser capture microdissection followed by real-time PCR BPOZ and TIAP/m-survivin expressed 4.5 and 3.4 fold higher in primary than primordial follicles, respectively. List of genes obtained from the present study will provide insights for the study of mechanism regulating primordial-primary follicle transition.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.1
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• pp.40-47
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• 2017

Granulosa cells, which surround the oocyte within the ovarian follicle, play an essential role in creating conditions required for the development of oocytes and follicles. The solute carrier family (SLC) is comprised of influx transporters of steroidal hormones, various drugs, and several other substrates. The differential expression of selected DEGs was confirmed using in situ hybridization analysis. SLC23A3 and SLC39A10 were highly expressed in the ovary. The SLC39A10 gene was expressed in the primordial follicle stage, but SLC23A3 was expressed in the growing follicle stage. Contrastingly, the expression of SLC23A3 was increased in granulosa cells at the growing follicle stage. The differential expressions of SLC23A3 and SLC39A10 between the primordial and primary follicles were additionally confirmed by using follicle isolations. The gene expression profile from the present study may provide insight for future studies on the mechanism(s) involved in primordial-primary follicular transition and suggestions to promote follicular development in ovarian dysfunction.