• Clinical and Experimental Reproductive Medicine
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• v.12 no.1
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• pp.83-98
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• 1985

In order to study the mechanism of follicular atresia, the follicles of the porcine ovary were isolated according to the presence or absence of the corpus luteum and their size, and then classified to the normal? or atretic?follicle on the morphological observation such as the transparency, the vascularization of follicle, the nuclear phase of oocyte, and the homogeneity of the granulosa cell layer. The viability of granulosa cells was examined. The concentrations of progesterone ($P_4$), testosterone (T), and estradiol-17 beta ($E_2$) in each follicular fluid were estimated by the radioimmunoassay. The viability of granulosa cells in the atretic follicle was much lower than that of the normal one. The concentration of each steroid hormone increased as the follicular size was increased, was not different in quantity between the normal- and the atretic follicle of which diameter was below 3mm, and were much higher in the atretic follicle than those in the normal one of which diameter was above 7mm. The ratio of the concentration of E2 to T in the large atretic follicle valued higher than that in the normal one, but smaller in the small and medium atretic follicle than that in the normal one. The present study suggests that the mechanism of atresia of the large follicle may be different from that of the small and the medium follicle and that the amount of steroid hormones regarded as the one of the criteria for the atretic follicles.

• Molecules and Cells
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• v.38 no.4
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• pp.304-311
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• 2015

Most follicles in the mammalian ovary undergo atresia. Granulosa cell apoptosis is a hallmark of follicle atresia. Our previous study using a microRNA (miRNA) microarray showed that the let-7 microRNA family was differentially expressed during follicular atresia. However, whether the let-7 miRNA family members are related to porcine (Sus scrofa) ovary follicular apoptosis is unclear. In the current study, real-time quantitative polymerase chain reaction showed that the expression levels of let-7 family members in follicles and granulosa cells were similar to our microarray data, in which miRNAs let-7a, let-7b, let-7c, and let-7i were significantly decreased in early atretic and progressively atretic porcine ovary follicles compared with healthy follicles, while let-7g was highly expressed during follicle atresia. Furthermore, flow cytometric analysis and Hoechst33342 staining demonstrated that let-7g increased the apoptotic rate of cultured granulosa cells. In addition, let-7 target genes were predicted and annotated by TargetScan, PicTar, gene ontology and Kyoto encyclopedia of genes and genomes pathways. Our data provide new insight into the association between the let-7 miRNA family in granulosa cell programmed death.

• Development and Reproduction
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• v.4 no.1
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• pp.13-17
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• 2000

Follicle stimulating hormone (FSH) stimulates follicle growth, and inhibits the follicle atresia in the immature rodent ovaries. The present study was carried out to know the histological changes of ovarian follicles after FSH treatment in the prepubertal mice. Ten i.u. of recombinant FSH was i.p. injected on 3 weeks old mice. After the treatment, at 1, 2 and 3 days, left ovaries were collected for the histological study. The atretic ratio of preantral follicles increased with time after FSH treatment. However, in the case of antral follicles, there was no significant change in the ratio. The degenerating follicles contained apoptotic granulosa cells, macrophage, and polymorphonuclear leukocytes in the follicular cavity. The present results suggest that follicular degeneration caused by FSH hyperstimulation could be mediated by apoptosis as well as the acute inflammation.

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.142.1-142
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• 1996

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 1996.04a
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• pp.44.1-44
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• 1996

No Abstract, See Full Text

• Reproductive and Developmental Biology
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• v.35 no.3
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• pp.341-348
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• 2011

Sloan-Kettering virus gene product of a cellular protooncogene c-Ski is an unique nuclear pro-oncoprotein and belongs to the Ski/Sno proto-oncogene family. Ski plays multiple roles in a variety of cell types, it can induce both oncogenic transformation and terminal muscle differentiation when expressed at high levels. The aim of the present study was to locate Ski protein in rat ovaries in order to predict the possible involvement of Ski in follicular development and atresia. First, expression of c-Ski mRNA in the ovaries of adult female rats was confirmed by RT-PCR. Then, ovaries obtained on the day of estrus were subjected to immunohistochemical analysis for Ski and proliferating cell nuclear antigen (PCNA) in combination with terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). Ski was expressed in granulosa cells that were positive for TUNEL, but negative for PCNA, regardless of the shape and size of follicles. Expression of Ski in TUNEL-positive granulosa cells, but not in PCNA-positive granulosa cells, was also verified in immature hypophysectomized rats having a single generation of developing and atretic follicles by treatment with equine chorionic gonadotropin (eCG). These results indicate that Ski is profoundly expressed in the granulosa cells of atretic follicles, but not in growing follicles, and suggest that Ski plays a role in apoptosis of granulosa cells during follicular atresia.

• The Korean Journal of Zoology
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• v.30 no.4
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• pp.351-370
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• 1987

This experiment has been done in order to study the correlation between the ultrastructure changes and the atresia phenomenon of the follicles in porcine ovary. The ovaries were assorted according to the presence or absence of corpus luteum. Thereafter, the follicles were classified into normal, pyknotic, necrotic and cystic groups by atretic characteristics on the histological observation, and then their ultrastructures were examined with an electron microscope. The results were as followings. 1. In normal group, granulosa cells represented the ultrastructural characteristics of protein-synthesizing cells. Since the initiation of atresia, the line structure of granulosa cells showed many of the characteristic features of steroid-secreting cells, followed by gradual pyknosis. 2. In necrotic group of the ovary without corpus luteum, the theca interns became hypertrophic and displayed the ultrastructural features of active steroidsecreting cells. But this phenomenon was not seen in the follicles of the ovary with corpus luteum. 3. Degenerative changes of cumulus cells were similar to those of granulosa cells, and the degenerating oocytes showed the degeneration of cellular organelles, cytoplasmic vacuolization and disappearance of microvilli on the surface. The degeneration of granulosa cells tended to procede that of oocytecumulus complex in the follicles of the ovary having no corpus luteum, but this tendency was reversed in the case of presence of corpus luteum. In conclusion, it may be unable to identi(y the initiation of follicular atresia

• Development and Reproduction
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• v.1 no.1
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• pp.67-77
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• 1997

Mammalian ovary consists of various growing stages of follicles. Ovarian follicular growth and differentiation, however, can be distinguished into recruitment, growth, selectiona nd ovulation. while only minute of the selected follicles ovulate their oocytes, all the rest follicles disappear by atresia. this atresia is an important event of which physiological mechanism must be resolved. The present study was carried out to investigate the effects of various doses of pregnant mare's serum gonadotropin (PMSG) on the oocyte quality, ovulation rate, and the early embryonic development in immature mice. Immature mice were administrated with 5, 20, or 40 IU PMSG. At every 12 hour up to 72 hour after treatment, body and ovary weights were measured. Oocytes were flushed from the oviducts under the dissecting microscope and observed under the inverted microscope. Late 2-cell embryos were collected from the mice which were superovulated by the same dosage of PMSG followed by 5 IU hCG 47 hours after PMSG-treatment. The percentage of abnormal oocytes was higher in 20 or 40 IU PMSG-treated animals than 5 IU PMSG-treated ones. Ovulation occured at 12 hours afger PMSG injection in all experimental groups. The percentage of retrieved abnormal oocytes increased in the 20 or 40 IU PMSG-treated goups but not in 5 IU PMSG-treated group. There was no significant difference in the mating rate among the groups [52.6% (10/19), 66.7% (10/15), 44.0% (11/25) : 5, 20, 40 IU group respectively] ; however, ther was a significant (p<0.01) increase of embryo retrieval rates in 5 and 20 IU-treated groups compared with that in 40 IU-treated group [89.2% (239-268), 85.5% (224/262), 40.0% (18/45)]. There was significant (p<0.01) increase of embryo development rates in 5 IU-treated group compared with that in 20 and 40 IU-treated group [231/239(96.7), 179/224(79.9), 77.8(14/18)]. In conclusion, higher doses of PMSG injection increased the occurrence of abnormal oocytes ovulation in immature mice. The most of oocytes collected from 5 or 20 IU-PMSG-treated group has fertilizabioity. But in mice injected iwth higher doses of PMSG, their oocytes exhibit less fertilizability and, even fertilized, all oocytes are not fully capable of development.

• Development and Reproduction
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• v.20 no.4
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• pp.315-329
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• 2016

Fas ligand (FasL) and its receptor Fas have been implicated in granulosa cell apoptosis during follicular atresia. Although interferon-gamma (IFN-${\gamma}$) is believed to be involved in the regulation Fas expression in differentiated granulosa or granulosa-luteal cells, the expression of this cytokine and its role in the regulation of the granulosa cell Fas/FasL system and apoptosis during follicular maturation have not been thoroughly investigated. In the present study, we have examined the presence of IFN-${\gamma}$ in ovarian follicles at different stage of development by immunohistochemistry and related their relative intensities with follicular expression of Fas and FasL, and with differences in granulosa cell sensitivity to Fas activation by exogenous agonistic Anti-Fas monoclonal antibody (Fas mAb). Although IFN-${\gamma}$ immunostaining was detectable in oocyte and granulosa cells in antral follicles, most intense immunoreactivity for the cytokine was observed in these cells of preantral follicles. Intense immunoreactivity for IFN-${\gamma}$ was most evident in granulosa cells of atretic early antral follicles where increased Fas and FasL expression and apoptosis were also observed. Whereas low concentrations of IFN-${\gamma}$ (10-100 U/mL) significantly increased Fas expression in undifferentiated granulosa cells (from preantral or very early antral follicles) in vitro, very higher concentrations (${\geq}1,000U/mL$) were required to up-regulate of Fas in differentiated cells isolated from eCG-primed (antral) follicles. Addition of agonistic Fas mAb to cultures of granulosa cells at the two stages of differentiation and pretreated with IFN-${\gamma}$ (100 U/mL) elicited morphological and biochemical apoptotic features which were more prominent in cells not previously exposed to the gonadotropin in vivo. These findings suggested that IFN-${\gamma}$ is an important physiologic intra-ovarian regulator of follicular atresia and plays a pivotal role in regulation of expression of Fas receptor and subsequent apoptotic response in undifferentiated (or poorly differentiated) granulosa cells at an early (penultimate) stage of follicular development.

• The Korean Journal of Zoology
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• v.33 no.1
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• pp.63-69
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• 1990

To study the follicular atretic mechanism in mammalian ovary, the medium-sized (3.0-6.0mm) follicles of porcine ovary were morphologically classified as nonnal and atretic. Steroid concentrations in the follicular fluid were analyzed by radioimmunoassay, and the proteins in that fluid were electrophoretically separated. Concentrations of progesterone in the atretic follicular fluid of follicular phases were higher than those of normal ones (p < 0.05). Concentrations of testosterone were high in normal luteal and atretic follicular-phases follicles. The concentrations of estradiol remained significanily lower in atretic follicular-phases follicles than normal. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis of follicular fluid proteins, four kinds of proteins (20K, 32K, 33K, 38K) were detected, and those proteins were not present in sera. According to the ovarian cycle, proteins of MW of 112K and 141K were identified. In atretic follicular fludies, MW of 23K and 24K were specifically detected. From the above results, we can conclude that, as ovarian cycle changes, steroid contents and protein composition in atretic follicular fluid are different from the normal developing follicular fluid. To further understand the physiologic roles of the proteins present in the atretic follicular fluids, these proteins need to be characterized and identified.