• Journal of Animal Science and Technology
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• 제54권3호
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• pp.165-174
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• 2012

For horse breeders or managers, it is critical to understand the estrous cycle of mares. Breeding of mares cannot be successfully achieved throughout the whole year as mares breed seasonally. Mares are only able to breed when day length is more than 16 h, and this period is known as the breeding season. Their estrous cycle is approximately 21 days with 5-7 days of estrus and 14 to 15 days of a diestrus period. The estrous cycle of the mare is mainly controlled by gonadotropins, which control follicular development and ovulation. Mares exhibit unique ovulatory events which are not observed in other species. A LH surge occurs for several days, with levels of LH reaching their peak after ovulation. The LH level at the time of LH peak is lower than most other species. The unique anatomical structure of the ovaries of mares is known to limit the number of eggs ovulated. Several attempts have been made to develop chemical/hormonal agents which might be used to manipulate the timed ovulation of mares. Agents that have been tested include hCG, native GnRH, Deslorelin (Ovuplant, GnRH-agonist), Buserelin (GnRH analogue), equine pituitary extracts and equine chorionic gonadotropin (eCG or PMSG). However, the function, purity or stability of these agents is not reliable. Recombinant equine LH, an alternative agent for the timed ovulation, has been developed and tested for its biological activities, through the use of both in vitro and in vivo experiments. The reLH was suggested to be a reliable agent in inducing ovulation within 48 h after being administered through injection, when the size of dominant follicle is 35 mm in diameter.

• 한국발생생물학회지:발생과생식
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• 제4권2호
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• pp.187-193
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• 2000

양식산 농어, Lateolabrax japonius 암컷의 난소와 혈액을 1997년부터 1999년까지 매년 10월부터 2월까지 2회 반복 채취하였다. Gonadosomatic index는 11월부터 증가하기 시작하여 12월(12.8$\pm$1.5)과 1월(14.8$\pm$3.5)에 최고 수준을 나타낸 후 2월(2.6$\pm$1.5)에는 급격히 감소하였다(P<0.05). 난소내 난모세포는 12월과 1월에 3차 난황구기까지 발달하고 성장이 완료되지만, 성숙 및 배란이 되지 않고 2월에는 퇴화되었다. 혈중 estradiol-l7$\beta$의 농도는 11월부터 증가하기 시작하여 12월 (1,152.3$\pm$107.2 pg/ml)과 1월(1,315.4$\pm$99.5 pg/ml)에 최고 수준을 나타낸 후 2월에는 급격히 감소하였다(P<0.05). 17 $\alpha$,20-dihydroxy-4-pregnen-3-one는 실험기간 동안 낮은 농도(86.6$\pm$6.5~93.8$\pm$2.8 pg/ml)를 유지하며 유의한 변화는 없었다(P<0.05). 성장이 완료된 난모세포를 갖고 있는 양식산 농어에 HCG를 주사(1,000 IU/kg과 2,000 IU/kg)하면 모든 개체에서 성숙 및 배란이 유도되었다. HCG 농도에 따른 수정율과 부화율은 차이가 없었으나, 부상란 수는 1,000 lU/kg에서 325,000$\pm$26,000개, 2,000 IU/kg에서 195,000$\pm$35,000개로 차이가 있었다. 이상의 결과를 종합하면, 양식산 농어 암컷은 양식환경 하에서도 난황형성 및 난모세포의 성장은 정상적으로 진행되지만, gonadotropin의 surge가 일어나지 않아 최종성숙과 배란이 되지 않는 것으로 추정되었다. 농어에서 난모세포의 인위적 성숙 및 배란 유도에 의한 난 생산은 HCG 1000 IU/kg가 효과적이었다.

• Clinical and Experimental Reproductive Medicine
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• 제31권4호
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• pp.225-234
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• 2004

Objectives: To evaluate the efficacy of GnRH antagonist cetrorelix in women undergoing controlled ovarian hyperstimulation (COH) for in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) and to determine changes in serum hormone concentrations during cetrorelix administration. Methods: We performed a clinical trial on 30 patients undergoing COH with highly purified follicular stimulating hormone (HP-FSH) and gonadotropin releasing hormone antagonist (GnRHant), cetrorelix. FSH was administrated from day 2 or 3 of cycle with fixed dose and adjusted according to individual response. 0.25 mg of cetrorelix was injected daily subcutaneously from stimulation day 5 until the day of hCG administration. Daily ultrasound monitoring was performed for growing follicles and serum levels of luteinizing hormone (LH), estradiol ($E_2$) and progesterone were measured daily during cetrorelix administration. Up to 4 embryos were transferred. Results: Mean age of enrolled patients was $32.0{\pm}3.4$ years (mean $\pm$ S.D.). All of 30 patients underwent oocyte pick-up, and embryo transfer was done in 28 patients. The total and mean numbers of received oocytes were 196 and $6.5{\pm}4.7$, the number of fertilized eggs was 111, and the fertilization rate was 56.6%. Total duration of FSH administration was $9.2{\pm}2.2$ days and mean of $24.3{\pm}7.7$ ampules of HP-FSH was administered. Total duration of cetrorelix administration was $5.7{\pm}1.9$ days. Serum LH and progesterone levels were maintained in the range of $1.4{\sim}2.9\;mIU/mL$ and $0.3{\sim}0.6\;ng/mL$, which respectively reflected effective prevention of premature LH surge. Clinical pregnancies were achieved in 9 patients, and overall clinical pregnancy rate was 30.0% per oocyte retrieval, and 32.1% per embryo transfer. Conclusion: GnRH antagonist is safe and convenient for COH for IVF-ET and effective with optimal pregnancy rate.