• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.1-6
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• 2006

Abstract - Global decline in wildlife mammals has been accelerated during past decades. Especially the conservation the wild life mammals in polar areas, is urgent. In an effort to understand the reproduction of the seals dwelling in the polar area, spermatogenesis in the seals was reviewed. Seals breed seasonally and in most of the seal species, delayed implantation is frequently observed. To date, histological and endocrinological evaluation revealed highly cyclic nature in supermatogenesis and steroidogenesis in testis. Seasonal changes in blood testosterone level together with melatonin is closely related with changes in light cycle between summer and winter. In adult testis at breeding seasons, spermatogenesis is manifested by consecutive 18 stages of germ cell development. Three kinds of Leydig cells different in steroidogenic activity as well as cellular morphology appear during the testis development. During non-breeding season, spermatogenic arrest and Leydig cell hypoplasia are frequently found. Interestingly, blood circulation through the anastomoses of pelvic veins cooled the testes and thus guarantees spermatogenesis within the body trunk. Endocrine disruptors and heavy metals have been found in the body tissues of several seals species and alter steroidogenesis in seals, suggesting environmental pollutants together with decrease in habitats are potentially threatening the reproductive success in seal species.

• Clinical and Experimental Reproductive Medicine
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• v.20 no.1
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• pp.19-29
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• 1993

Plasminogen activator (PA)-plasmin system in follicular fluid is involved in the process leading to follicular rupture at ovulation. It is well known that PA is closely associated with cellular differentiation and tissue remodeling on evidences from the study of normal and malignant tissues. This study was designed to ascertain a potential role of PA in the ovarian folliculogenesis. Immature Sprague-Dawley rats were injected with pregnant mare serum gonadotropin, followed by injection of serine protease inhibitor (SPI; mixture of 1 mol/L benzamidine and 1 mol/L amino-caproic acid) into the unilateral ovarian bursa. In the control study, mechanical effect of bursal injection and contralateral ovarian effect SPI were ruled out. Total antral follicular areas relative to total ovarian cross-sectional areas was siginificantly lower in SPI-injected ovary than in saline-injected ovary. SPI injection decreased the relative antral follicular area by 33 % respectively. Electron microscopic finding of granulosa cell in the atretic follicle showed the presence of pyknotic nucleus, blurring of neucleolemma, degeneration of mitochondria and dilation of endoplasmic reticulum. After induction of ovulation with hCG, the number of oocytes released was significantly decreased in SPI-injected oviduct than in saline-injected oviduct. From above results, author discussed that PA may play a role not only in ovulation but also in some processes of folliculogenesis.

• Clinical and Experimental Reproductive Medicine
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• v.8 no.2
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• pp.1-11
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• 1981

The quantitative analyses of the phosphatase activity in the endometrium of the rat ovariectomized on Day 2 of pregnancy was carried out in comparison with the intact one, in order to investigate the hormonal dependency of the uterus prior to the implantation, and to study the phosphatase activity in the endometrial tissues in vitro incubated in different acidity of the medium. The results obtained were as follows: 1. The activity of the total phosphatase was the highest at Day 3 of pregnancy of the intact animals irrespective of acidity of the medium. However, the ovariectomized rat showed its peak somewhat delayed. The time of the highest activity of the enzymes was matched with the time of high secretion of the ovarian hormones. 2. The activity of acid phosphatase in the endometrium was twice or four times as much high as that of neutral or alkaline phosphatase, respectively. 3. The activity of alkaline phosphatase was rather steady in Day 3 through Day 5 of the pregnancy of the rat intact or ovariectomized but with low level compared to those of other phosphatase. 4. The present re~lt indicated more important role by $Mg^{2+}$-dependent phosphatase than by $K^+$-dependent one for the preparation for decidualization.

• Clinical and Experimental Reproductive Medicine
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• v.48 no.4
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• pp.303-310
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• 2021

Decorin (DCN) is a proteoglycan belonging to the small leucine-rich proteoglycan family. It is composed of a protein core containing leucine repeats with a glycosaminoglycan chain consisting of either chondroitin sulfate or dermatan sulfate. DCN is a structural component of connective tissues that can bind to type I collagen. It plays a role in the assembly of the extracellular matrix (ECM), and it is related to fibrillogenesis. It can interact with fibronectin, thrombospondin, complement component C1, transforming growth factor (TGF), and epidermal growth factor receptor. Normal DCN expression regulates a wide range of cellular processes, including proliferation, migration, apoptosis, and autophagy, through interactions with various molecules. However, its aberrant expression is associated with oocyte maturation, oocyte quality, and poor extravillous trophoblast invasion of the uterus, which underlies the occurrence of preeclampsia and intrauterine growth restriction. Spatiotemporal hormonal control of successful pregnancy should regulate the concentration and activity of specific proteins such as proteoglycan participating in the ECM remodeling of trophoblastic and uterine cells in fetal membranes and uterus. At the human feto-maternal interface, TGF-β and DCN play crucial roles in the regulation of trophoblast invasion of the uterus. This review summarizes the role of the proteoglycan DCN as an important and multifunctional molecule in the physiological regulation of oocyte maturation and trophoblast migration. This review also shows that recombinant DCN proteins might be useful for substantiating diverse functions in both animal and in vitro models of oogenesis and implantation.

• Development and Reproduction
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• v.25 no.3
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• pp.157-171
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• 2021

To determine whether the reproductive processes of sea bass, Lateolabrax japonicus, proceed normally after transportation from an outdoor net-cage into indoor tanks, we examined changes in the gonadosomatic index (GSI), histological gonadal tissue, and plasma levels of sex hormones (testosterone and estradiol-17ß) during their annual reproductive cycle. We also measured maturation and spawning across two sea water salinity levels (full and low salinity). Fecundity was estimated by the relationship between egg number and body size in female sea bass. Monthly changes in the GSI, histological gonadal tissues, and oocyte size showed both male and female sea bass reach final maturation in January and February, respectively, indicating that the spermiation of males occurs earlier than the spawning of females. The histological results indicated that the sea bass is a multiple spawner, similar to many marine teleosts, exhibiting group-synchronous oocyte development. Female maturation and spawning were enhanced in lower salinity seawater (29.6-31.0 psu) compared to that of normal salinity (34.5-35.1 psu). These results confirm that sea bass reproduction can occur successfully in captivity and imply that fertilized eggs can be collected from February to March. Additionally, our results show that lower salinity enhances oocyte maturation and spawning of female sea bass.

• Development and Reproduction
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• v.5 no.1
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• pp.1-8
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• 2001

Golden hamsters show the reproductive activity that is determined by the photoperiod (length of light per day). Photoperiod is an environmental factor that is predictable through an entire year. The hamsters are sexually active in summer during which day length exceeds night time. The critical length is at least 12.5 hours of light in a day where reproductive function is maintained. The information of photoperiod is mediated by the pineal gland because removal of pineal gland blocks the influence of photoperiod on reproductive activity. The hamsters without pineal gland maintain sexual activity and promote it in a situation that suppresses gonadal activity. The pineal gland secretes melatonin that reflects the photoperiod. The appropriate administrations of melatonin into both pineal intact and pinealectomized hamsters lead to a gonadal reression. The results suggest that melatonin constitutes a part of control mechanism whereby environmental information is transduced to neuroendocrine signal respensible for the functional integrity of the reproductive system. Despite of the intense studies, the action site of melatonin is on the whole unknown. It is mainly due to the lack of acute efffct of melatonin on the secretion of reproductive hormones. However, sexually regressed animals display the low levelsof gonadotropins and the augmentation of the hypothalamic gonadotropin-releasing hormone (GnRH) content, implying that the antigonadotropic effects either by photoperiod and/or by the treatment of melatonin are mediated by the GnRH neuronal system. The action mechanism by which melatonin exerts its effect on GnRH neuron needs to be investigated. Recent cloning of melatonin receptor will contribute to examine various and putative potencies of melatonin via its anatomical identification and the action mechanism of melatonin on target tissues at the molecular level.

• Clinical and Experimental Reproductive Medicine
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• v.25 no.2
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• pp.161-170
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• 1998

Protein expression patterns of matrix metalloproteinases (MMPs) were examined in mouse reproductive organs during estrous cycle. Estrous cycle was classified into diestrus, proestrus, estrus or metestus and MMP expression was analyzed by zymography using gelatin as a substrate. Uterine fluid (UF) obtained both at diestrus and proestrus exhibited 4 major MMPs including 106kDa, 64kDa, 62kDa and 59kDa gelatinases. However, in UF at estrus, the gelatinolytic activity of 64kDa MMP disappeared and that of 106kDa and 62kDa MMPs dramatically decreased. At metestrus, 64kDa MMP activity reappeared and 106kDa and 62kDa MMP exhibited increased activities such that the band intensity of 106kDa was comparable to that in UF at diestrus. Gelatinolytic activity of 59kDa MMP was not changed throughout the cycle. Both ovarian and oviductal tissue homogenate revealed 4 MMPs which corresponded to the 4 MMPs of UF. However, unlike UF MMPs, gelatinolytic activity of these MMPs did not show distinct changes throughout the cycle. Either an inhibitor of MMP, 1,10-phenanthroline, or a metal chelator, EDTA, abolished the appearance of the above MMP activities in gelatinated gel whereas a serine proteinase inhibitor, phcnylmethylsulfonyl fluoride, failed to inhibit the appearance of MMP activities, proving that gelatinolytic activity of the above reproductive tissues were due to the enzymatic activity of MMP. When gclatinolytic activity of mouse serum was examined, it revealed 5 MMPs (131kDa, 106kDa, 89kDa, 64kDa and 62kDa bands) and one gelatinase (84kDa) band. From these results, it is concluded that the protein expression of MMPs of mouse reproductive organs, particularly uterus, is temporally regulated during estrous cycle and uterine 106kDa, 64kDa and 62kDa MMPs are suggested to play an important role in cyclic tissue remodeling of mouse uterus.

• Development and Reproduction
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• v.13 no.3
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• pp.183-190
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• 2009

In mammals, puberty is a dynamic transition process from infertile immature state to fertile adult state. The neuroendocrine aspect of puberty is started with functional activation of hypothalamus-pituitary-gonadal hormone axis. The timing of puberty can be altered by many factors including hormones and/or hormone-like materials, social cues and metabolic signals. For a long time, attainment of a particular body weight or percentage of body fat has been thought as crucial determinant of puberty onset. However, the precise effect of high-fat (HF) diet on the regulation of hypothalamic GnRH neuron during prepubertal period has not been fully elucidated yet. The present study was undertaken to test the effect of a HF diet on the puberty onset and hypothalamic gene expressions in immature female rats. The HF diet (45% energy from fat, HF group) was applied to female rats from weaning to around puberty onset (postnatal days, PND 22-40). Body weight and vaginal opening (VO) were checked daily during the entire feeding period. In the second experiment, all animals were sacrificed on PND 36 to measure the weights of reproductive tissues. Histological studies were performed to assess the effect of HF diet feeding on the structural alterations in the reproductive tissues. To determine the transcriptional changes of reproductive hormone-related genes in hypothalamus, total RNAs were extracted and applied to the semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Body weights of HF group animals tend to be higher than those of control animals between PND 22 and PND 31, and significant differences were observed PND 32, PND 34, PND 35 and PND 36 (p<0.05). Advanced VO was shown in the HF group (PND $32.8{\pm}0.37$ p<0.001) compared to the control (PND $38.25{\pm}0.25$). The weight of ovaries (p<0.01) and uteri (p<0.05) from HF group animals significantly increased when compared to those from control animals. Corpora lutea were observed in the ovaries from the HF group animals but not in control ovaries. Similarly, hypertrophy of luminal and glandular uterine epithelia was found only in the HF group animals. In the semi-quantitative RT-PCR studies, the transcriptional activities of KiSS-1 in HF group animals were significantly higher than those from the control animals (p<0.001). Likewise, the mRNA levels of GnRH (p<0.05) were significantly elevated in HF group animals. The present study indicated that the feeding HF diet during the post-weaning period activates the upstream modulators of gonadotropin such as GnRH and KiSS-1 in hypothalamus, resulting early onset of puberty in immature female rats.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.3
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• pp.149-157
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• 2007

Objective: This study was performed to compare the expression of osteopontin (OPN) mRNA and protein in the eutopic and ectopic endometrial tissues in women with endometriosis and endometrial tissues in women without endometriosis. Methods: A total of 32 women with histologically confirmed endometriosis were recruited for study group. For controls, 34 women undergoing operative treatment for cervical intraepithelial neoplasia (CIN) or benign gynecologic condition other than endometriosis were recruited. At the time of laparoscopy or laparotomy, a biopsy specimen was taken from the endometrial cavity and peritoneal endometrial implant or endometrioma whenever appropriate. We employed real time quantitative RT-PCR to quantify OPN mRNA expression of these tissues and performed western blot analysis to measure the quantity of OPN. Results: The expression of OPN mRNA was significantly higher in both eutopic and ectopic endometrial tissues of women with endometriosis than in endometrial tissues of controls during both proliferative and secretory phase. In the eutopic endometrial tissue of women with endometriosis, OPN mRNA expression significantly increased during the secretory phase compared to the proliferative phase in women with endometriosis as well as controls. However, in the ectopic endometrial tissue, OPN mRNA expression significantly decreased during the secretory phase compared to the proliferative phase. The expression of OPN protein was significantly higher in women with endometriosis than in controls. Conclusion: This study shows the marked expression of OPN mRNA and protein in eutopic and ectopic endometrial tissues in women with endometriosis may be associated with the adhesion and invasion of endometrial explants.

• Korean Journal of Ichthyology
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• v.5 no.2
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• pp.226-234
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• 1993

Cobitis sinensis-longicorpus complex considered as hybrid origin between C. sinensis and C. longicorpus coccurred ommonly in the upper streams of the Nakdong River, Korea. Histological examinations of their gonad were accompanied with 272 individuals of C. sinensis-longicorpus complex collected. Most of fishes collected were females, however, only 6 individuals were found males. The ovarian tissues of females are completely fertile undergoing normal oogenensis. In the male gonads, testicular lobule structure with abnormal vacuolar tissues were observed. Spermatogonia and spermatocytes were also observed of their testis however spermatids or sperms were not shown in their developmental stages. From these facts, we infer that female population of C. sinensis-longicorpus complex may be unique reproductive hierarchy accomplishing their reproduction with participation of males of their closely related bisexual species.