• Asian-Australasian Journal of Animal Sciences
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• v.13 no.3
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• pp.390-400
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• 2000

The corpus luteum (CL) is a temporary endocrine gland whose main function is to secrete progesterone to support pregnancy. On the other hand, the cyclic bovine CL has also been shown to be a site of prostaglandin $F_{2{\alpha}}$ ($PGF_{2{\alpha}}$) production. Although there is general agreement that endometrial $PGF_{2{\alpha}}$ is an essential luteolysin in cattle, luteal $PGF_{2{\alpha}}$ seems to play a luteotropic role as an autocrine and/or paracrine factor, especially for the development and maintenance of the CL. This supposition is based on evidence that some of the prerequisites for autocrine/paracrine mechanisms are present, including local production of $PGF_{2{\alpha}}$ and the existence of specific binding sites within the CL. The purpose of this paper is to review the regulation of luteal $PGF_{2{\alpha}}$ secretion, its action on CL as an autocrine and/or paracrine factor and the receptivity of bovine CL to. $PGF_{2{\alpha}}$.

• Journal of Embryo Transfer
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• v.27 no.4
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• pp.211-221
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• 2012

The process of embryo implantation requires physical contact and physiological communication between the conceptus trophectoderm and the maternal uterine endometrium. During the peri-implantation period in pigs, the conceptus undergoes significant morphological changes and secretes estrogens, the signal for maternal recognition of pregnancy. Estrogens secreted from the conceptus act on uterine epithelia to redirect $PGF_2{\alpha}$, luteolysin, secretion from the uterine vasculature to the uterine lumen to prevent luteolysis as well as to induce expression of endometrial genes that support implantation and conceptus development. In addition, conceptuses secrete cytokines, interferons, growth factors, and proteases, and in response to these signals, the uterine endometrium produces hormones, protease inhibitors, growth factors, transport proteins, adhesion molecules, lipid molecules, and calcium regulatory molecules. Coordinated interactions of these factors derived from the conceptus and the uterus play important roles in the process of implantation in pigs. To better understand mechanism of implantation process in pigs, this review provides information on signaling molecules at the conceptus-uterine interface during early pregnancy, including recently reported data reported.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.5
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• pp.486-490
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• 1998

The present study examined the follicular populations prior to and during superovulation and investigated their relationship with superovulatory response in crossbred cattle. Eleven animals were administered i.m. 8 doses of Folltropin of 2.5 ml each (1.75 mg/ml) spread over 4 days beginning on Day 10 of oestrous cycle, and 30 and 20 mg Lutalyse was given alongwith the 5th and 6th injections of Folltropin, respectively, to induce luteolysis. The animals were artificially inseminated 48, 60 and 72 h after the first Lutalyse injection. The number of corpora lutea (CL) was recorded by palpation per rectum and embryos were recovered non-surgically on Day 6 (Day 0 day of superoestrus). The ovarian follicular population was examined by transrectal Ultrasonography 15 h prior to and 52 h after the first FSH injection, and then on the day of superoestrus and the day of flushing. The follicles were classfied on the basis of diameter as small (3-5 mm), medium (6-9 mm) and large (${\geq}10mm$). The total number of follicles increased significantly (p < 0.01) from $2.45{\pm}0.35$, 15 h prior to the first FSH injection to $8.09{\pm}1.12$, 52 h after the first FSH injection and then further to $13.27{\pm}1.89 $ on the day of superoestrus. A positive correlation was observed between the number of small follicles 15 h prior to the first FSH injection (r = 0.60, p < 0.05), the number of large follicles 52 h after the first FSH injection (r=0.59, p < 0.05) and the number of CL. The follicular population prior to and during superovulation was, however, not significantly different between high (> 6 CL) and low responders (${\leq}6CL$). The present study suggests that the follicular populations undergo dynamic changes during superovulation and that follicular populations prior to superovulation have a limited application as an indicator of the superovulatory response.

• Journal of Embryo Transfer
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• v.13 no.2
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• pp.179-190
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• 1998

Prolactin (PRL) surge in cycling rats at proestrous afternoon has previously been reported as an inducer of apoptotic cell death of luteal cells. This death-inducing action of PRL seeins unusual, because PRL can he categorized as a cell-survival factor, if other known physiological functions of PRL are taken into account. In this study, the apoptotic action of PRL was assessed in cultured cells prepared from rat luteal tissue and underlying molecular /cellular mechanism of PRL-induced luteolysis was analyzed. The latest crop of corpora lutea (CLs) were enucleated from rat ovaries at 18:00 h on the proestrous day before the next ovulation. Donor rats were pretreated with CB154, a dopamine agonist, in order to he exempted from the endogenous PRL surge. The harvested GLs were dispersed and cultured with or without PRL (2$\mu$g /ml) for 24 or 48 h. An addition of PRL to the culture medium changed the parameters indicative of cell death via apoptosis: a decrease in cell viability (MTT) and an increase in chromatin condensation. Most of the DNA breakdown in nuclei induced by PRL occurred in steroidogenic cells which were identified by 3$\beta$-HSD activity staining, and the number of 3$\beta$-HSD-positivecells were significantly decreased. Interestingly, most of the cells with an apoptotic nucleus adhered to one or more intact and seemingly non-steroidogenic cells. Because the expression of Fas has heen shown to be abundant in murine ovary, and Fas is known to have an exact physiological role in occurrence of apoptotic cell death, the membrane form-Fas ligand (rnFasL) was quantified in the cell lysate. An addition of PRL increased expression of mFasL. Moreover, an addition of concanavalin A (ConA), a T-cell specific activator, in place of PRL, enhanced the apoptotic parameters. Cumulatively, the apoptotic PRL action was addressed to cells unknown than steroidogenic lute~ cells. The most prohable candidate for the direct target cells is Tcells in the luteal tissue that can express mFasL in response to PRL.

• Development and Reproduction
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• v.1 no.1
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• pp.79-89
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• 1997

Recent studies have demonstrated that apoptotic cell death plays an important role in the mechanism underlying follicular atresia and luteolysis. However, the mechanisms responsible for initiating these processes have not been elucidated. In in vitro fertilization (IVF) programs, it is highly possible that continuous and repeated administration of FSH/hMG and GnRH agonists for the usage of ovarian hyperstimulation may induce apoptotic death of granulosa cells leading to atresia in the human ovarian follicles. The present study was performed to investigate whether FSH/hMG and GnRh agonists used for a longer period in controlled ovarian hyperstimulation has any effect on the apoptosis of granulosa-luteal (GL) cells obtained from hyperstimulated ovaries. To examine apoptotic cell death in the GL cells, cells were stained with acridie orange followed by observed in some of GL cells. Similar but distinct staining of apoptotic GL cells was observed when the cells were examined by using in situ TUNEL method. The healthy-looking cells with normal nuclear morphology were not stained, whereas cells with pyknotic nuclei or with apoptotic nuclei were intensively stained. After examining the ultrastructural features of GL cells by TEM, it was confirmed that the majority of cells seemed to have normal nuclei while GL cells undergoing apoptotic cel death were rarely found. The DNA extracted from GL cells showed a typical pattern of fragmentation following DNA electrophoretic analysis. We have confirmed that the apoptosis occurs in granulosa-luteal cells obtained from hyperstimulated ovaries. Technically, in situ apoptosis detection method is simple and reproducible and is well suited to identify the quality of oocytes retrieved from hyperstimulated ovaries.

• Reproductive and Developmental Biology
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• v.38 no.1
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• pp.9-19
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• 2014

For successful embryo implantation, the communication of the maternal endometrium with the conceptus trophectoderm is required essentially. In pigs, conceptuses undergo morphological change in length to enlarge the physical contact area with the maternal endometrium and secrete estrogen to induce the maternal recognition of pregnancy during the peri-implantation period. Conceptus-derived estrogen prevents luteolysis by conversion in direction of $PGF_{2{\alpha}}$ secretion from the uterine vasculature to the uterine lumen as well as it affects on expression of the uterine endometrial genes. In addition to estrogen, conceptuses release various signaling molecules, including cytokines, growth factors, and proteases, and, in response to these signaling molecules, the maternal uterine endometrium also synthesizes many signaling molecules, including hormones, cytokines, growth factors, lipid molecules, and utilizes ions such as calcium ion by calcium regulatory molecules. These reciprocal interactions of the conceptus trophectoderm with the maternal uterine endometrium make development and successful implantation of embryos possible. Thus, signaling molecules at the maternal-conceptus interface may play an important role in the implantation process. This review summarized syntheses and functions of signaling molecules at the maternal-conceptus interface to further understand mechanisms of the embryo implantation process in pigs.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.5
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• pp.626-631
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• 2005

Nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) is involved in cell apoptosis, which contributes to luteal regression and luteolysis in some species. In large domestic animals, no direct evidence for the relationship between NO and cell apoptosis in the process of corpus luteum regression is reported. The present study was conducted to investigate the localization of iNOS on porcine corpora lutea (CL) during the oestrus cycle and its relation to cell DNA fragmentation and CL regression. According to morphology, four luteal phases throughout the estrous cycle were defined as CL1, CL2, CL3 and CL4. By isoform-specific antibody against iNOS, the immunochemial staining was determined. Luteal cell DNA fragmentation was determined by flow cytometry. The results showed that no positive staining for iNOS was in CL1 and that iNOS was produced but limited to the periphery of CL2, while in the CL3, the spreading immunochemical staining was found inside the CL. No iNOS positive staining was detected in CL4. Meanwhile, DNA fragmentation increased dramatically when CL developed from CL2 to CL3 (p<0.05). In CL4, higher proportion of luteal cells still had fragmented DNA than that of luteal cells from CL1 or CL2 (p<0.05). These results indicate that iNOS expression is closely related to luteal cell apoptosis and then to luteal regression.

• Development and Reproduction
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• v.13 no.1
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• pp.51-57
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• 2009

Monocyte chemoattractant protein-1(MCP-1) is released from the macrophages and endothelial cells, regulated luteotropic and luteolytic actions of macrophages and induced luteolysis. However, the mechanisms of MCP-1 on the development and maintenance of pregnant corpora lutea are thoroughly unknown. In this experiment, TUNEL stain, ED1, ED2, and MCP-1 immunohistochemistry on the corpora lutea of pregnant rats were carried out to reveal the role of macrophages in the developing corpora lutea. In the postpartum corpora lutea, the number of macrophages was increased significantly, and the intensity of ED1 and ED2 immunoreactivity in macrophages were increased moderately, and MCP-1 immunoreactivity was also increased. In conclusion, macrophages in the postpartum corpora lutea may exert phagocytic action mainly, and the macrophages in the pregnant corpora lutea maintain the structure and function of lutein cells.

• Korean Journal of Animal Reproduction
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• v.16 no.2
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• pp.103-107
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• 1992

The present study was conducted to find out the changes of progesterone levels in pre and post partum by the PGF2$\alpha$ administration to control artificial parturition in Korean native goats. A total of 24 goats were offered for this experiment. The animals were divided into 4 goats per treatment by the administration time(142, 145 or 148 day of pregnancy). Blood samples were taken from jagular vein pre-post partum by the PGF2$\alpha$ intramuscular administration. The progesterone in serum was assayed by radioimmunoassay. The serum progesterone level in late-pregnant goats averaged 4.85$\pm$0.55ng/ml, 4.05$\pm$0.47ng/ml or 2.76$\pm$0.25ng/ml on 142, 145 or 148 days of gestation. After the intramuscular injection with PGF2$\alpha$ for inducing parturition, it decreased remarkably to below 1.0ng/ml and to the base level(0.4~0.6ng/ml) at day 1 after parturition. And then this base level of progesterone was maintained until the final examination at 9 days of postpartum. No significant difference was found in the serum levels of progesterone between the doses treated for parturition induction. It was concluded that exogenous PGF2$\alpha$, administrated intramuscularly, induced premature parturition with causing withdrawal of progesterone levels for triggering luteolysis.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.4
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• pp.404-409
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• 1998

Nine cows were superovulated by administration of 8 injections of Folltropin each (2.5 ml/injection, 1.75 mg/ml) i.m spread over 4 days, beginning on Day 10 of oestrous cycle, and 30 and 20 mg prostaglandin $F_{2{\alpha}}$ was given along with the 5th and 6th injections of Folltropin, respectively, to induce luteolysis. The animals were artificially inseminated 48, 60 and 72 h after the first prostaglandin $F_{2{\alpha}}$ injection. The number of corpora lutea was recorded by palpation per rectum and by ultrasonography on Day 6 (Day 0 = day of oestrus). The ovaries were examined daily by ultrasonography on Days 3-9 of the oestrous cycle for following the growth and regression of the largest follicle, which was considered the morphologically dominant follicle. The animals were classified into two groups depending upon the presence (n = 4) and absence of a dominant follicle (n = 5). There was a high correlation (r = 0.97, p < 0.001) between the number of corpora lutea observed by palpation per rectum and that determined by ultrasonography. Mean (${\pm}SEM$) number of corpora lutea determined by ultrasonography ($11.20{\pm}3.71$ vs $3.25{\pm}0.75$) and by palpation per rectum ($10.40{\pm}3.91$ vs $2.25{\pm}0.75$) was significantly higher (p < 0.05) in the nondominant group compared to that in the dominant group. There was no difference in the numbers of follicles 2-3 mm ($13.80{\pm}4.49$ vs $8.00{\pm}1.08$), 4-6 mm ($7.00{\pm}1.87$ vs $3.50{\pm}1.33$), and the total number of follicles ${\geq}2mm$ ($22.00{\pm}5.95$ vs $12.50{\pm}1.26$) between the two groups, one day prior to initiation of superovulation. There was, however, a significant (p<0.01) positive correlation between the number of corpora lutea with the numbers of follicles 2-3 mm (r = 0.83), 4-6 mm (r = 0.80) and the total number of follicles ${\geq}2mm$ (r = 0.89) observed one day prior to initiation of superovulation. The results of this study indicate that the presence of a dominant follicle adversely affects the superovulatory response in cattle.