• 한국발생생물학회지:발생과생식
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• 제20권4호
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• pp.289-296
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• 2016

This report describes the sex differentiation of the Korean rose bitterling, Rhodeus uyekii, from hatching to 170 days post-hatch (DPH) in relation to total length (TL), body weight (BW), and integral water temperature (IWT). The growth curve of TL from just hatching to 83 DPH was $5.144e^{0.045t}$ ($R^2=0.961$; t, time), and that of BW was $2.398e^{0.086t}$ ($R^2=0.725$). Primordial germ cells (PGCs) were observed at 17 DPH (7.9 mm TL, 3.74 mg BW, $374^{\circ}C$ IWT), and thereafter began to protrude into the peritoneal cavity. At 21 DPH ($9.2{\pm}0.14mm$ TL, $4.8{\pm}0.07mg$ BW, $462^{\circ}C$ IWT), some PGCs contained condensed chromatin and oocyte were observed in meiotic prophase. In contrast to the ovaries, which grew gradually after sexual differentiation, testes began multiplying at 25 DPH (10.1 mm TL, 5.42 mg BW, $550^{\circ}C$ IWT), when testicular differentiation was first identified, and multiplied continuously thereafter. At 33 DPH (11.2 mm TL, 10.5 mg BW, $726^{\circ}C$ IWT), the developing testes contained spermatogonia that exhibited mitotic activity. No spermatocyte or sperm cell was observed until 83 DPH (18.9 TL, 48.2 mg BW, $1,826^{\circ}C$ IWT). At 170 DPH (32.5 mm TL, 270.1 mg BW, $3,740^{\circ}C$ IWT), which was the end point of this study, the mature ovaries showed germinal vesicle breakdown, while the mature testes contained observable spermatocytes and sperm cells. These results allow us to identify the sex differentiation type of the Korean rose bitterling as differentiated gonochoristic.

• 한국발생생물학회지:발생과생식
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• 제17권4호
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• pp.435-440
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• 2013

Previous studies, including our own, have demonstrated that the intratesticular injection of hypertonic saline (20%) decreased serum testosterone level which was similar to the surgical castration in the rat, showing the state of chemical castration. In the present study, we further verify the efficacy of this less invasive method as an alternative of surgical orchidectomy in the andrological field. Sterilized 20% saline was directly injected into the adult male rats (750 ${\mu}l$ per testis). The tested rats were divided into 3 groups including intact group (intact), orchidectomy group (ORX) and saline injection group (SAL) after bilateral orchidectomy was performed at the same day of injection. All rats were sacrificed at 4 weeks after injection. The reproductive organs (testes, epididymis, seminal vesicles and prostates) were collected and used for DNA and protein pattern analyses. Also, patho-histological studies on the testes were performed. In contrast to the intact group, similar DNA damages of testis and seminal vesicle were appeared in ORX group and SAL group. The DNA degradations seemed to be the results of necrosis rather than apoptosis. In the protein pattern analysis, all the testing tissues exerted similar patterns in the ORX group and the SAL group compared to the those of intact group. Patho-histological studies revealed that severe degenerative changes in testicular seminiferous tubules and massive infiltration of immune cells in SAL group. The present study confirmed that direct injection of hypertonic saline into the testis caused the equivalent biochemical changes in the accessory sex organs as shown in the orchidectomized animals. These results suggest that hypertonic saline injection model could be a useful castration model which can substitute for surgical castration when its safety is secured through further study in the future.

• 한국발생생물학회지:발생과생식
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• 제27권3호
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• pp.149-157
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• 2023

We investigated the involvement of autophagy with steroidogenesis in testicular Leydig cells. Human chorionic gonadotropin (hCG)-stimulated T production in Leydig cells was not remarkably altered in the presence of an autophagy inhibitor 3-methyladenine (3-MA). Although pretreatment with 3-MA demonstrated a tendency to decrease hCG-induced T production, the differences were significant only at a higher time point of 24 h following hCG. Microtubule associated protein light chain 3 (LC3)-II was detectable in the control cells in all the experiments. The hCG-induced increase in steroidogenic acute regulatory protein (StAR) and cytochrome P450 side chain cleave (P450scc) protein levels were not significantly altered by 3-MA. Leydig cells isolated from immature rat testes 12 h following hCG treatment showed relatively increased levels of LC3-II protein compared to the control group. Furthermore, LC3-II levels shown in these cells reached almost the identical to those from normal adult testes. However, LC3-II protein levels were almost comparable or even slightly lower than the controls at 48 h following hCG. Expression of StAR and P450scc was upregulated at both 12 and 48 h after hCG. We also used MA-10 cells, the mouse Leydig cell line, in this experiment. When dibutyryl cyclic-AMP was treated with MA-10 cells, P4 levels were significantly increased in the cell culture medium. However, P4 levels tended to decrease in the presence of 3-MA, but the difference was not statistically significant. This was consistent with the results of the rat Leydig cell experiments. Together, we believe that although autophagy participates in steroidogenesis and enhances steroidogenic efficacy of Leydig cells, it may not be a decisive cellular process for steroidogenesis, specifically in the mature Leydig cells.

• Parasites, Hosts and Diseases
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• 제22권2호
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• pp.181-189
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• 1984

우리나라산(전남 강진 및 경남 금해시)미꾸리에서 이전고무극구흡충(Echinostoma cinetorchis)의 피낭유충을 처음으로 검출하고 횐쥐에 감염시킨 후 성충을 얻어 종을 확인하였다. 또, 미꾸리의 피낭유충 감염상황과 횐쥐에서의 간단한 발육과정을 관찰하였다. 결과를 요약하면 다음과 같다. 1. 미꾸리 46마리중 5마리 (10.9%)에서 담낭유충이 검출되었고 감염된 미꾸리당 감염대은 평균 34.4개이었다. 피낭유충은 미꾸리의 후복벽에서만 발견되었다. 2. 실험감염 횐쥐에서 감염 6∼28일까지 총 충체회수률은 24.6%이었으며 감염기간이 길어짐에 따라 회수률은 감소되었다. 3. 충체는 두증과 두련(37∼38개)이 뚜렷하고 고환이 이전하거나 소실되는 점으로 보아 E. sinetorchis Ando et Ozaki, 1923로 동정되었다. 4. 충체의 발육은 감염6일부터 10일 사이에 가장현저하였으며 이 기간중 특히 생식기관의 발육이 비생식기관에 비해 빠르고 현저하였다. 이상의 결과로 볼 때 우리나라에서 미꾸리가 이전고구극구흡충의 제이중간숙주 역할을 하고 있음이 입증되었고 실험적으로 얻은 성충의 형태에서 고구의 이전 또는 소실이 종의 특성임이 재확인되었다.

• Journal of Animal Science and Technology
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• 제64권4호
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• pp.654-670
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• 2022

Spermatogenesis and testis development are highly structured physiological processes responsible for post-pubertal fertility in stallions. Spermatogenesis comprises spermatocytogenesis, meiosis, and spermiogenesis. Although germ cell degeneration is a continuous process, its effects are more pronounced during spermatocytogenesis and meiosis. The productivity and efficiency of spermatogenesis are directly linked to pubertal development, degenerated germ cell populations, aging, nutrition, and season of the year in stallions. The multiplex interplay of germ cells with somatic cells, endocrine and paracrine factors, growth factors, and signaling molecules contributes to the regulation of spermatogenesis. A cell-tocell communication within the testes of these factors is a fundamental requirement of normal spermatogenesis. A noteworthy development has been made recently on discovering the effects of different somatic cells including Leydig, Sertoli, and peritubular myoid cells on manipulation the fate of spermatogonial stem cells. In this review, we discuss the self-renewal, differentiation, and apoptotic roles of somatic cells and the relationship between somatic and germ cells during normal spermatogenesis. We also summarize the roles of different growth factors, their paracrine/endocrine/autocrine pathways, and the different cytokines associated with spermatogenesis. Furthermore, we highlight important matters for further studies on the regulation of spermatogenesis. This review presents an insight into the mechanism of spermatogenesis, and helpful in developing better understanding of the functions of somatic cells, particularly in stallions and would offer new research goals for developing curative techniques to address infertility/subfertility in stallions.

• Parasites, Hosts and Diseases
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• 제30권4호
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• pp.237-244
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• 1992

Meterchis orientalis의 병아리 숙주내 감염력 및 성장발육상을 알아 보고 성충의 형태학 적 특징을 관찰하였다. 참붕어로부터 분리 수집한 피리유충을 부화된지 3일된 병아리 40마리에 각각 100개씩 경구감염시킨 후 1.5, 3, 5, 7, 9, 11, 14일 및 21일에 충체를 누수하여 고정, 염색, 탈수 및 봉입 등의 과정을 거친 다음 관찰 및 계측하였다. 총체는 모두 병아리의 담낭에서 발견되었으며 평균 32U의 회수율을 나타내었다. 감염 후 9일까지는 비교적 완만히 성장하였으나 9일에서 11일 사이에는 급속히 성장하였고 11일에서 14일 사이에 다시 성장이 둔화하였으며 21일에 회수한 충체는 14일된 충체보다 크기가 작았다. 감염 후 1.5일파 5일에 요수한 충체에서는 비생식기관과 생식원기가 관찰되었고 5일된 충체에서는 비정형적인 난락와 엽상의 고구이 관찰되었으며 이후 차차 발육하여 감염 후 11일에 회수한 충체들은 완전히 성숙하였다. 성숙한 충체는 나뭇잎 모양이었으며 1∼3굽이의 저정낭, 타원형의 난소, 주머니 모양의 수정낭,517엽의 고환 및 소포형의 난황선 등을 보유하고 있었다. 충란은 평균 31.gx15.Sum 크기이었고 최대 폭이 가운데 지점에 있었으며 난개 반대편의 난각이 비후되어 있었다. 이상의 결과로 병아리가 M orienta비의 새로운 숙주로 추가되었고 이 흡충이 병아리 내에서 감염 후 21일까지 sigmoid형으로 성장하며 성충이 되기까지는 l1일 정도가 소요됨을 알 수 있었다.

• 항공우주기술
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• 제6권2호
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• pp.188-196
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• 2007

복합재 케이스는 KSLV-I 킥모터 시스템 요구 조건을 만족하도록 설계하였다. 비행모델 제작에 앞서 신뢰성을 확보하기 위해 구조시험과 연소시험을 수행하였다. 구조시험으로는 수압시험, 진공시험, 비 파괴검사를 수행하여 연소시험 전에 케이스의 구조적 건전성을 확인하였으며 지상연소시험을 통해 열적 구조적 특성을 고찰하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제4권1호
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• pp.1-5
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• 1991

Responsiveness of the testis to pregnant mare's serum gonadotropin (PMSG) was studied in immature Nili-Ravi buffalo bulls. Four month old bull calves weighing between 66 to 100 kg raised under uniform condition, were treated with 1000 IU PMSG or vehicle, daily, for six days. PMSG induced an increase in the size of the testis, enlargement of the seminiferous tubules and activation of the spermatogonia. The number of differentiated Leydig cells in the testis of gonadotropin treated animals increased considerably over that of the control testes. A significant increase in plasma testosterone concentrations was observed 24 h following the first injection of PMSG and the levels continued to increase until day 6. In vehicle treated animals plasma testosterone levels remained more or less at pretreatment values. The data suggest that buffalo bull testis is functionally responsive to gonadotropin at an early stage of prepubertal development.

• 한국발생생물학회지:발생과생식
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• 제14권2호
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• pp.99-105
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• 2010

정세관은 매우 복잡한 조직으로 마우스의 정자 발생 과정은 12단계로 구성되어 있다. Glutathione peroxidase(GPx)는 glutathione을 이용하여 과산화물(hydroperoxide)을 환원시키는 대표적인 항산화효소로서 포유류 정자 발생 과정에 관여하는 것으로 알려져 있다. 본 연구에서는 laser capture microdissection(LCM)을 이용하여 마우스 정소에서 발생 단계별로 정세관을 채취하여 real-time PCR로 cytosolic GPx(cGPx), gastrointestinal GPx(GI-GPx), plasma GPx(pGPx) 및 phospholipid hydroperoxide GPx(PHGPx)와 같은 GPx family 유전자의 발현 정도를 비교분석하였다. 동결절편(10 ${\mu}m$)은 정상 성숙 마우스의 정소를 사용하였다. LCM 방법으로 정세관의 단면을 I~V, VII~VIII, IX~XI 단계로 구별하여 채취하였다. PHGPx mRNA의 발현은 다른 GPx mRNA보다 정소에서 현저하게 높게 발현되었다. 정자 발생 단계에서 GI-GPx, pGPx 및 PHGPx의 mRNA는 VII~VIII 단계에서 가장 높았고 XI 단계 이후에 감소되었으며, I~V 단계에서 가장 낮은 발현을 보였다. 그러나, cGPx mRNA는 VII~VIII 단계에서 가장 높았고, XI~XI 단계에서 가장 낮은 발현을 보였다. 본 연구 결과, GPx family 유전자는 정자 발생 단계에서 서로 다르게 조절되며, LCM 방법은 정소세포의 정량 분석에서 유용하게 사용될 것으로 사료된다.

• 환경생물
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• 제24권1호
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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.