• Proceedings of the Korean Society of Developmental Biology Conference
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• 2005.10a
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• pp.80-80
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• 2005

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2005.10a
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• pp.80-80
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• 2005

• Clinical and Experimental Pediatrics
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• v.49 no.6
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• pp.610-616
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• 2006

Purpose : The purpose of this study was to evaluate the timing of sexual maturation and secular trends of menarchial age in Korean adolescents. Methods : Nine hundred eighty two school students and 119 university female students were included. Tanner's pubertal assessment method was applied using a self-assessment sheet with pictures for their developmental stages. A medical checkup database from 1,156,022 women was also used to analyze the age of menarche from the year 1900 to 1980. Results : Onset of puberty was at $11.3{\pm}1.3$ years(y) in girls and $12.1{\pm}1.5$ y in boys and total pubertal duration was 3.6 y in girls and 3.3 y in boys. Height at the onset of puberty was $146.1{\pm}7.9cm$ in girls and $152.7{\pm}9.8cm$ in boys. Weight at the onset of puberty was $39.3{\pm}6.9kg$ in girls and $47.7{\pm}14.4kg$ in boys. The mean age of menarche was $12.0{\pm}1.0y$ and mean age at nocturnal emission was $12.3{\pm}1.8y$. By age ten, 3.0 percent of girls experienced menarche, which increased to 41.1 percent by age 12, and 98.0 percent by age over 15. By SMR 2 breast stage, 18.2 percent of girls experienced menarche, which increased to 66.1 percent and 91.7 percent by SMR stages 3 and 4, respectively. By SMR 2 pubic hair stage, 52.0 percent and by SMR 3, 93.8 percent of girls experienced menarche. While the menarchial age of women born around 1980 was $12.4{\pm}1.1y$, the menarchial age of women born around 1990 was $12.0{\pm}1.1y$. Age at menarche has been advanced approximately by 2 years between 1900 and 1980 birth cohorts. Conclusion : There was a downward secular trend in pubertal timing. Age at menarche has been advanced by 2 years during the last 80 years. Further large scale, prospective studies, including inspection by specialists, are needed to provide reference data for pubertal timing in Korean adolescents.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.311-319
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• 2014

Early sexual maturation through temperature stimulation was induced in female and male of yezo scallop. Gonadosomatic index (GSI) in female showed $9.12{\pm}2.9$ in January, $14.89{\pm}2.9$ in February and $21.3{\pm}1.4$ in March in experiment I. GSI in experiment I showed a significant increase (P < 0.05) and in experiments II and III were not show significant variations (P > 0.05). It also showed significant between the control and the experiments I, II, and III in February (P < 0.05) measurements. Experiment I has showed good results in sexual maturation and spawning when compared with other experiments II and III and the control. Histological observation showed that ovary condition was in a growing stage in all the experiments I, II, and III. In February, ovary condition through histological observation was a late mature stage in all the experiments I, II, and III except the control of a growing stage. GSI and gonad weight were $4.4{\pm}0.88$ and 2.8 g, respectively in November whereas it was $15.1{\pm}2.8$, and 11.7 g, respectively in January and $21.7{\pm}5.4$, and 19.4 g, respectively in February after rearing at a water bath of $12^{\circ}C$ depending on the condition of experiment I. It was possible early releasing of eggs and sperms of yezo scallop in February instead of the middle of April to the end of May being spawning period. Fertilized eggs have become a gastrula stage through a spiral cleavage and then become a trochophore larvae after 36 hours. After 10 days, D-shaped larvae have changed into an umbo stage larvae and attached to juveniles in the post larvae after 20-23 days.

• Clinical and Experimental Pediatrics
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• v.52 no.12
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• pp.1370-1376
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• 2009

Purpose:Treatment of precocity with gonadotropin releasing hormone analogue (GnRHa) might theoretically exert a detrimental effect on the bone mass during pubertal development. We investigated the short-term changes in bone mineral density (BMD) during GnRHa treatment and the enhancement in the changes with the co-administration of GnRHa and human growth hormone (hGH). Methods:Forty girls with precocious or early puberty who were using GnRHa for more than 1 year were enrolled. Of them, 14 concurrently received hGH. Lumbar bone mineral density was measured before and after the treatment, and bone mineral density-standard deviation scores (BMD-SDSs) were compared according to chronologic age (CA) and bone age (BA), as well as according to the administration of GnRHa alone (Group I) or the co-administration of hGH and GnRHa (Group II). Results:BMDs before and after treatment were in the normal range according to CA but were significantly lower according to BA (P<0.05). During treatment, BMD-SDSs did not change according to CA but significantly increased according to BA (P<0.05). BMD-SDSs in group I did not change during treatment according to CA or BA, while those in group II increased significantly according to BA (P<0.05), but not according to CA. Conclusion:Lumbar BMD was adequate according to CA at initial manifestation of precocity but was lower if compared to BA, that is, BMD did not increase with BA. Because co-treatment with hGH significantly increased BMD-SDSs according to BA, hGH co-treatment could be considered during GnRHa therapy.

• Clinical and Experimental Pediatrics
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• v.52 no.1
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• pp.111-118
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• 2009

Puopose : Exposure to dietary phytoestrogens such as genistein during early childhood is a growing public health concern. We examined the effect of early exposure to genistein on sexual maturation in immature rats. Methods : Weaning (3wk-old) Sprague-Dawley female rats were assigned to three groups (n=6 for each): fed by high dose of genistein (100 mg/kg/d), low dose of genistein (10 mg/kg/d) and control group. First vaginal opening (VO) day was observed. Structural alterations in the ovary and uterus were assessed by histologically. Expression of genes of $ER{\alpha}$, $ER{\beta}$, and progesterone receptor (PR) in the ovary and uterus were investigated by RT-PCR. Results : High genistein group had earlier VO than control and low genistein group. Graafian follicles and corpora lutea were observed from the ovary of genistein-treated groups, while primary, secondary follicles and small atretic follicles were observed in the control group. Hypertrophy of luminal and glandular uterine epithelia were found in the genistein-treated groups while poor development of gland and fewer myometrial cell layers were evident in control group. In ovary, the transcriptional activities of $ER{\alpha}$ and $ER{\beta}$ were higher in high genistein group than in controls. In uterus, the transcriptional activities of $ER{\alpha}$, $ER{\beta}$ and PR were higher in low genistein group than in controls. Conclusion : Acute exposure to genistein during the prepubertal period could activate the reproductive endocrine system resulting in the early onset of puberty in female rats. Further clinical investigation on the effect of genistein on the sexual maturation in children is warranted.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.249-255
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• 2003

These studies were performed to improve the reproductive efficiency of gilts and we investigated the effects of puberty periods, first mating time and backfat thickness and will adapt to these results for early selection of excellent gilts. The main results were as follows; 1. First heats on birth season were showed 194.14 day, 163.25 day, 160.25 day and 157.92 day at birth of spring, summer, autumn and winter, respectively and birth of spring was significantly latest among other seasons (p<0.01). 2. First service on birth season were revealed 222.05 day in spring, 193.00 day in summer, 199.20 day in autumn and 190.11 day in winter. birth of spring was significantly latest among others (p<0.01). 3. First heat period of cadidated gilt had 13∼16 mm backfat thickness was 180.32 day, 171.24 day in 17∼20 mm and 162.20 day in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness. 4. First service of cadidate gilt had 13∼16mm backfat thickness was 211.12 day, 202.43 day in 17∼20 mm and 195.43 day in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness. 5. The litter size were 9.64 in gilts under 160 day of first heat, 10.14 in 161∼180 day, 9.56 in 181∼200 day and 9.13 in over 201 day. There showed the largest litter size in 161∼180 day of first heat but was no differences. 6. The litter size in gilts under 180 day of first service was 9.13, 9.75 in 181∼200 day, 10.13 in 201∼220 day and 9.45 in over 221 day. There showed the largest litter size in 201∼220 day of first service but was no differences. 7. The litter size of gilt had 13∼16 mm backfat thickness on first service was 9.33, 9.81 in 17∼20 mm and 10.17 in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness.