妊娠山羊黄体组织中ghrelin的表达

运用组织学和免疫组化方法对不同妊娠时期山羊黄体的组织学结构及ghrelin的分布规律进行了研究,结果表明:黄体外覆结缔组织性被膜,实质主要由粒性(大)黄体细胞和膜性(小)黄体细胞组成;在各时期均存在大黄体细胞的退化现象,退化黄体细胞数量随周期进程逐渐增多,结构变化表现为:细胞形态多变,胞质呈强嗜酸性,胞核固缩或碎裂.ghrelin阳性反应主要位于被膜和黄体细胞,各阶段被膜上均存在ghrelin表达,主要为纤维及血管的着色;黄体内ghrelin主要定位于大黄体细胞,另外部分小细胞也有表达,从分布范围和染色强度看,呈现出少-多再渐少的变化趋势;结合各周龄山羊黄体组织中ghrelin阳性产物相对表达量的分析,表明在妊娠早中期,黄体组织内有较高的ghrelin表达,而在妊娠后期表达较低.不同妊娠时期山羊黄体组织中ghrelin的这种周期性表达模式与黄体的功能相适应,提示ghrelin的表达与黄体的功能密切相关.     

FSH对多浪羊子宫和卵巢组织及血清生殖激素的影响

为了探讨外源激素卵泡刺激素(FSH)在诱导绵羊超数排卵过程中子宫和卵巢形态、卵泡数量及8种生殖激素浓度变化情况,试验选取30只健康经产多浪羊,随机均分为超数排卵(DC)组和同期发情(DT)组,同时埋植孕酮缓释硅胶栓(CIDR),记为第0天;DC组在埋栓后第11,12,13天依次递减注射FSH,DT组不做处理;在埋栓后第13天两组均撤栓并注射前列腺素(PG)。从埋栓第11天开始每组屠宰3只多浪羊,至第15天结束,摘取子宫和卵巢,观察子宫和卵巢形态,记录卵巢优势卵泡数量,采用ELISA试剂盒检测外源FSH处理后多浪羊血清中8种生殖激素FSH、促黄体生成素(LH)、雌激素(E2)、孕酮(P₄)、促性腺激素释放激素(GnRH)、PG、抑制素(INH)和瘦素(LEP)浓度的变化。结果表明：多浪羊经过埋栓处理后卵巢中优势卵泡数量随着时间推移先增加后减少,DC组的平均优势卵泡数量高于DT组。第15天DC组个别卵巢表面可观察到“红体”出现,而DT组未发现。在注射FSH后,DC组中FSH和LH激素浓度持续增加,第13,14天时显著高于第10～12天(P<0.05);E2浓度先...     

超排前有腔卵泡数对青年和牛体内胚胎生产效率的影响

为提高和牛体内胚胎生产效率,优化供体牛筛选标准,本实验选取68头青年黑毛和牛为供体,超排处理前使用B超检查两侧卵巢上直径为3～5 mm的有腔卵泡数,以卵泡总数10和20为临界值将其分为3组,Ⅰ、Ⅱ、Ⅲ组有腔卵泡数分别为<10、10～19、≥20个,以CIDR+FSH+PG法进行超排处理后人工授精,比较不同组间胚胎生产效率。结果表明:Ⅲ组黄体数(15.44)、回收胚胎数(13.13)及可用胚胎数(9.56)均显著高于其他2组(P<0.05),Ⅱ组黄体数、回收胚胎数及可用胚胎数显著高于Ⅰ组(P<0.05),即随着供体牛超排前有腔卵泡数增多,回收胚胎数及可用胚胎数随之增多;Ⅲ组胚胎可用率显著低于Ⅰ组,退化率显著高于Ⅰ组和Ⅱ组(P<0.05)。综上,有腔卵泡数对和牛胚胎生产效率有影响,可以作为供体牛筛选标准之一。     

P4及FSH处理对育成母羊卵泡发育和生殖激素分泌的影响

旨在研究孕激素(P₄)与促卵泡素(FSH)联合或单独使用对湖羊育成母羊卵泡发育及生殖激素分泌的影响。选择体况良好、发情周期正常的湖羊育成母羊80只,体质量(35.16±1.66)kg,利用P₄阴道栓+孕马血清促性腺激素+氯前列醇钠(P₄阴道栓+PMSG+PG)方法进行发情周期同步处理,选择撤栓后24～48 h发情的72只羊进入正式试验,撤栓后5 d记为试验第0天。将72只试验羊随机分为9组,每组8只,其中1,2,3组在第0天埋植P₄阴道栓,埋植持续时间分别为5,8,11 d; 4,5,6组用FSH处理,分别在试验的第4,7,10天肌肉注射FSH 2次(早上8:00注射70 IU和下午6:00注射30 IU);7,8,9组P₄+FSH联合处理,在第0天埋植P₄阴道栓,埋植持续时间分别为5,8,11 d,并在第4,7,10天肌肉注射FSH 2次(时间、剂量同4,5,6组)。9组试验羊分别在第0,5,8,11天静脉采血,并手术观察记录卵泡数。结果显示,试验9组卵...     

促性腺激素抑制激素基因疫苗pVAX-RFRP和抑制素基因疫苗pXAIS对水牛卵泡发育的影响

40头奶水牛分4组,每组10头。Ⅰ组:p VAX-RFRP质粒肌注+p XAIS质粒肌注+p XAIS活菌苗喷鼻;Ⅱ组:p XAIS质粒肌注+p XAIS活菌苗喷鼻;Ⅲ组:p VAX-RFRP质粒肌注;Ⅳ组:PBS肌注对照。研究抑制素基因疫苗(p XAIS)和促性腺激素抑制激素基因疫苗(p VAX-RFRP)对水牛发情和卵泡发育的影响。结果表明:Ⅰ组和Ⅲ组水牛很快发情,与Ⅳ组(PBS对照)差异显著(P0.05),Ⅱ组与Ⅳ组(PBS对照)差异不显著,3个试验组之间差异不显著。3个试验组总卵泡数都比对照组多(P0.05),Ⅱ组大卵泡数较多,与Ⅳ组(PBS对照)差异显著(P0.05),各试验组间大卵泡数不存在显著差异。结果表明,两种疫苗都显著促进水牛发情,并有利于大卵泡发育。     

外源激素处理提高小尾寒羊和蒙古羊春季繁殖力的研究

旨在研究春季对小尾寒羊、蒙古羊进行同期发情与人工授精处理时,不同外源激素使用对两品种羊繁殖指标和血液生殖激素浓度的影响。挑选春季小尾寒羊、蒙古羊母羊各120只,按不同外源激素处理方法随机均分为4组,其中对照组处理方法为阴道氟孕酮海绵栓(FGA)+撤栓后即注射孕马血清促性腺激素(PMSG),试验Ⅰ组为FGA+撤栓前24 h注射PMSG,试验Ⅱ组为FGA+撤栓前24 h注射PMSG+注射促黄体素释放激素A₃(LHRH-A₃),试验Ⅲ组为FGA+撤栓前24 h注射PMSG+注射LHRH-A₃+稀释精液中添加催产素(OXT)。结果：试验I组与对照组相比,蒙古羊放栓第14天孕激素(P₄)浓度显著升高(P<0.05),卵泡刺激素(FSH)浓度和发情反应率均极显著升高(P<0.01);试验Ⅱ组与试验Ⅰ组相比,小尾寒羊产羔率极显著提高(P<0.01),蒙古羊放栓第14天FSH、促性腺激素释放激素(GnRH)浓度和同期受胎率均极显著升高(P<0.01),同期妊娠率显著提高(P<0.05)...     

皮下埋植法诱发家免卵泡发育的试验初报

本试验通过将FSH与聚乙烯吡咯烷酮(PVP)和明胶混合制成药棒(试验Ⅰ组)、FSH与PVP和丝胶混合制成药棒(试验Ⅱ组)、FSH+PVP+明胶+涂凡士林+涂FSH粉剂(试验Ⅲ组)、FSH+PVP+丝胶+涂凡士林+涂FSH粉剂(试验Ⅳ组),皮下埋植给2～3月龄的幼兔,并与空白组(对照组1,无激素处理组)、肌注FSH组(对照组2)进行比较.5 d后所诱发的大卵泡数分别为3.6±1.6、3.8±1.0、7.5±1.0、6.5±1.6个;两个时照组的大卵泡数分别为2.3±2.3、11.6±2.6个.试验Ⅲ、Ⅳ组、对照组2的大卵泡数明显多于对照组1,也多于Ⅰ、Ⅱ组.在青年兔的试验中,对照组1、试验Ⅰ、Ⅲ组的大卵泡数分别为3±1.4、4.8±2.8、15.4±8.0个.     

皮下埋植法诱发家兔卵泡发育的试验初报

本试验通过将FSH与聚乙烯吡咯烷酮(PVP)和明胶混合制成药棒(试验Ⅰ组)、FSH与PVP和丝胶混合制成药棒(试验Ⅱ组)、FSH+PVP+明胶+涂凡士林+涂FSH粉剂(试验Ⅲ组)、FSH+PVP+丝胶+涂凡士林+涂FSH粉剂(试验Ⅳ组),皮下埋植给2～3月龄的幼兔,并与空白组(对照组1,无激素处理组)、肌注FSH组(对照组2)进行比较。5d后所诱发的大卵泡数分别为:3.6±1.6、3.8±1.0、7.5±1.0、6.5±1.6个;两个对照组的大卵泡数分别为:2.3±2.3、11.6±2.6个。试验Ⅲ、Ⅳ组、对照组2的大卵泡数明显多于对照组1,也多于Ⅰ、Ⅱ组。在青年兔的试验中,对照组1、试验Ⅰ、Ⅲ组的大卵泡数分别为3±1.4、4.8±2.8、15.4±8.0个。     

肉鸡不同生长时期光照模式研究

研究探索了优质肉鸡不同生长时期的最佳光照模式,以期优化生殖系统发育及全面提升生产性能。选用0日龄的优质肉鸡S3系母鸡540只,每组180只,分别针对育雏期、育成期和产蛋期设计三种不同类型的光照模式饲养于三间封闭式鸡舍内,试验期66周。结果表明:(1)14周龄时,第Ⅱ组卵巢表面开始密布着小黄卵泡和大白卵泡,至开产周龄时第Ⅱ组较第Ⅰ组和第Ⅲ组明显密集(P0.05),卵泡表面相对更为光滑;23周龄时,第Ⅱ组输卵管长度更长、管壁更厚(P0.05)。(2)整个产蛋期第Ⅱ组的产蛋率、蛋重和日产蛋量显著高于Ⅰ组和Ⅲ组(P0.05),产蛋后期Ⅰ组产蛋率开始显著低于Ⅲ组(P0.05)。整个产蛋期Ⅱ组料蛋比显著低于Ⅰ组和Ⅲ组(P0.05),死淘率高于Ⅰ组(P0.05),低于Ⅲ组(P0.05)。(3)整个产蛋期内,蛋壳强度、蛋黄重表现为Ⅰ和Ⅲ组显著小于Ⅱ组,产蛋后期蛋壳强度表现为Ⅲ组显著高于Ⅰ组(P0.05),蛋黄重表现为Ⅲ组显著低于Ⅰ组(P0.05)。(4)相关性分析表明了输卵管长与输卵管管壁厚度、最大卵泡直径和产蛋率呈极显著正相关(P0.01),与大、小黄卵泡数、蛋重等呈显著正相关(P0.05)。综合比较三组光照模式,第Ⅱ组在生殖系统发育、产蛋性能及蛋品质方面最优。     

伊维菌素微球在山羊体内的药效学研究

探讨新型制剂伊维菌素微球在山羊体内的药效学。选取32只山羊〔平均体重(27.05±1.20)kg〕,随机分成4组(Ⅰ^Ⅳ),每组7Ⅳ),每组7⁹只。Ⅰ组0.3 mg/kg体重,皮下注射伊维菌素注射液;Ⅱ和Ⅲ组3 mg/kg体重,分别皮下注射伊维菌素PLA5微球和PLGA微球混悬液;Ⅳ组作为对照组,不给药,对山羊粪便虫卵数(EPG)进行检测。Ⅰ、Ⅱ组和Ⅲ组山羊在第14天虫卵减少率均为100%,虫卵全部转阴;在给药后91 d虫卵减少率分别为0、74.3%和80.0%、;在给药后123 d分别为0、61.8%和0。伊维菌素对山羊胃肠道线虫虫卵具有较好的驱除作用,PLGA微球和PLA5微球的药效维持长达120 d左右,表现出长效作用。     

The induction of a delayed post-ovulatory progesterone rise in dairy cows: a novel model

A delayed rise in post-ovulatory progesterone is associated with poor embryo development in the cow, although the underlying cause of this aberrant luteal function is poorly understood. The objective of this study was to develop a novel model, in which a delayed progesterone rise could be induced by manipulating the dynamics of the follicular phase. Luteolysis was induced in 20 dairy cows in the presence of either a larger follicle > 10 mm (LF, n = 11) or a smaller follicle < 10 mm (SF, n = 9) and transrectal ultrasonography was performed to determine follicle and CL growth and timing of ovulation. Plasma progesterone and oestradiol were analysed 3x daily. Cows were slaughtered on either day 4 (n = 4 per group) or day 7 (SF, n = 5; LF, n = 7) after ovulation. The pre-ovulatory follicle was larger in the LF group than the SF group at luteolysis (13.5 +/- 0.4 mm versus 6.7 +/- 0.7 mm, P < 0.001) and ovulation (16.7 +/- 0.3 mm versus 13.6 +/- 0.6 mm, P < 0.001). The LF group experienced a shorter follicular phase and ovulated 36 h earlier than the SF group (P < 0.001). At luteolysis, plasma oestradiol concentrations were greater in the LF group (P < 0.001), although peak concentrations were not different (P > 0.05). Moreover, higher progesterone concentrations were observed in the LF group during the early luteal phase (P < 0.05). Luteal weights were positively correlated with plasma progesterone concentrations on day 5 (P < 0.05) but not day 8. In conclusion, a model has been developed which has shown that the dynamics of follicle development during the pre-ovulatory period is an important determinant of subsequent CL development and function.     

Changes in Ovarian Follistatin Levels During the Oestrous Cycle in Sheep may Serve as an Intraovarian Regulator

The expression and concentration of follistatin and activin change during oestrous cycle suggesting their involvement in the regulation of follicular development. The aim of this study was to determine the level, source and potential role of follistatin in the sheep ovary. Follistatin in ovarian venous blood, measured by radioimmunoassay, remained at its low level from follicular phase (day ?1 and 0) to mid‐luteal phase (days 11–13) phase but were significantly elevated during the late luteal phase (days 14 and 15) when corpora lutea underwent regression. Western blot analyses of follicular fluid at day 15 of the cycle showed two strong bands at 42 and 45 kDa and weakly stained bands at 39 and 31 kDa. At day 0, these bands became weaker and the 39 kDa band became undetectable. However, there were no differences in follistatin concentrations between ovaries with and without functional corpus luteum (CL) during the whole luteal phase. In addition, although the ovaries of Booroola ewes normally contain more corpora lutea than those of normal merino ewes, follistatin concentrations in both jugular and ovarian venous blood were similar in Booroola and normal merino ewes. It is concluded that the secretion of follistatin from the ovary is not related to the formation of CL or high ovulation rate of Booroola ewes. The elevation in follistatin concentration in follicular fluid and ovarian blood during late luteal phase may indicate a dual role of follistatin in the luteolysis of existing CL and development of new follicle cohort.     

Size Distribution of Dispersed Luteal Cells During Oestrous Cycle in Angora Goats

The present study examines the size distribution of the goat steroidogenic luteal cells throughout the oestrous cycle. Corpora lutea (CL) were collected after laparatomy on days 5, 10 and 16 of the oestrous cycle. Luteal cells were isolated from CL by collagenase digestion. Steriodogenic luteal cells were identified by staining of the cells for 3beta-hydroxysteroid dehydrogenase activity, a marker for steroidogenic cells. Luteal cells having steroidogenic capacity covered a wide spectrum of sizes, ranging from 5 to 37.5 microm in diameter. There was a significant increase in mean cell diameters (p < 0.01) as CL aged. The mean cell diameter on day 5 was 11.55 +/- 0.12 microm, which was significantly increased and reached up to 19.18 +/- 0.24 mum by day 16 of the oestrous cycle. The ratio of large to small luteal cells was 0.06:1.0 on day 5 of the oestrous cycle. This ratio increased to 0.78:1.0 by day 16 of the oestrous cycle. Luteal cell size on days 5, 10 and 16 of the oestrous cycle reached its maximum at 7.5, 10 and 35 microm in diameter, respectively. Development of CL is associated with an increase in luteal cell size in goats. It is likely that small luteal cells could develop into large luteal cells as CL becomes older during oestrous cycle in goats.     

Blood flow: a key regulatory component of corpus luteum function in the cow

Prostaglandin F2alpha (PGF2alpha) is the primary luteolysin in the cow. During the early luteal phase, the corpus luteum (CL) is resistant to the luteolytic effect of PGF2alpha. Once mature, the CL becomes responsive to PGF2alpha and undergoes luteal regression. These actions of PGF2alpha coincide with changes in luteal blood flow (BF): PGF2alpha has no effect on BF in the early CL, but acutely increases BF in the peripheral vasculature of the mature CL within 30 min of PGF2alpha injection. During spontaneous luteolysis, luteal BF increases on Days 17-18 of the estrous cycle, prior to any decrease in plasma progesterone (P). The increase in luteal BF is synchronous with an increase in plasma PGFM levels, suggesting that pulsatile release of PGF2alpha from uterus stimulates the increase in luteal BF. Serial biopsies of these CL showed that mRNA expression for endothelial nitric oxide synthase (eNOS) together with endothelin-1 (ET-1) and angiotensin converting enzyme (ACE) increases on Days 17-18 when the luteal BF is elevated. On Day 19 when plasma P level firstly decreases, eNOS mRNA returns to the basal level whereas ET-1 and ACE mRNA remains elevated. Cyclooxygenase-2 (COX-2) mRNA expression increases on Day 19. In support of these data, an in vivo microdialysis study revealed that luteal ET-1 and angiotensin II (Ang II) secretion increases and precedes PGF2alpha secretion during spontaneous luteolysis. In conclusion, we show for the first time that an acute increase of BF occurs in the peripheral vasculature of the mature CL together with increases in eNOS expression and ET-1 and Ang II secretion in the CL during the early stages of luteolysis in the cow. We propose that the increase in luteal BF may be induced by NO from large arterioles surrounding the CL, and simultaneously uterine or exogenous PGF2alpha directly increases ET-1 and Ang II secretion from endothelial cells of microcapillary vessels within the CL, thereby suppressing P secretion by luteal cells. Taken together, our results indicate that an acute increase in luteal BF occurs as a first step of luteolysis in response to PGF2alpha. Therefore, local BF plays a key role to initiate luteal regression in the cow.     

Acquisition of luteolytic capacity involves differential regulation by prostaglandin F2alpha of genes involved in progesterone biosynthesis in the porcine corpus luteum

Luteolytic capacity is defined as the ability of corpora lutea (CL) to undergo luteolysis after prostaglandin (PG) F2alpha treatment. The mechanisms causing acquisition of luteolytic capacity are not yet identified but CL without luteolytic capacity have PGF2alpha receptors and respond to PGF2alpha with some changes in gene expression. Inhibition of progesterone biosynthesis is a key feature of luteolysis and therefore we postulated that genes involved in progesterone biosynthesis would be regulated by PGF2alpha differently in CL with or without luteolytic capacity. Gilts on day 9 after estrus (lack luteolytic capacity) or day 17 of pseudopregnancy (with luteolytic capacity) were treated with saline or a PGF2alpha analog (cloprostenol) and CL were collected 0.5 (Experiment I) or 10 h (Experiment II) later. In Experiment III, large luteal cells from CL on day 9 or 17 were cultured for 1, 12 and 24h with or without PGF2alpha. PGF2alpha decreased LDL receptor mRNA (27%), steroidogenic acute regulatory protein (StAR) mRNA (41%), StAR protein (75%), LH receptor mRNA (55%), and LH receptor protein (45%) at 10 h after treatment in day 17 but not day 9 CL. PGF2alpha increased DAX-1 mRNA at 0.5 h (43%) and 10 h (46%) after PGF2alpha in day 17 but not day 9 CL but decreased 3betaHSD mRNA ( approximately 20% at 10 h) in both days 9 and 17 CL. In vitro, PGF2alpha decreased StAR mRNA at 12 h only in day 17 luteal cells; however, continuous treatment with PGF2alpha for 24 h decreased StAR mRNA in both days 9 and 17 luteal cells. Thus, luteolytic capacity involves a critical change in responsiveness of DAX-1, StAR, and LH receptor to PGF2alpha that results in inhibition of luteal progesterone biosynthesis.     

Role of tumor necrosis factor-alpha and nitric oxide in luteolysis in cattle

Although prostaglandin (PG) F2alpha is known to be a principal luteolytic factor, its action on the bovine corpus luteum (CL) is mediated by other intra-ovarian factors. Tumor necrosis factor-alpha (TNFalpha) and its specific receptors are present in the bovine CL with the highest expressions at luteolysis. TNFalpha in combination with interferon-gamma reduced progesterone (P4) secretion, increased PGF2alpha and leukotriene C4 (LTC4) production, and induced apoptosis of the luteal cells in vitro. Low concentrations of TNFalpha caused luteolysis, which resulted in a decreased level of P4, and increased levels of PGF2alpha, LTC4 and nitrite/nitrate (stable metabolites of nitric oxide-NO) in the blood. Inhibition of local NO production counteracts spontaneous and PGF2alpha-induced luteolysis. Therefore, NO is a likely candidate for the molecule that mediates PGF2alpha and TNFalpha actions during luteolysis. Both PGF2alpha and TNFalpha increase NO concentrations in blood, and stimulate NO synthase expression on protein level in the bovine CL cells. NO stimulates PGF2alpha and LTC4 secretion, inhibits P4 production and reduces the number of viable luteal cells. TNFalpha and NO induce apoptotic death of the CL by modulating expression of bcl-2 family genes and by stimulating expression and activity of caspase-3. The above findings indicate that TNFalpha and NO play crucial roles in functional and structural luteolysis in cattle.     

Toll‐like receptor and related cytokine mRNA expression in bovine corpora lutea during the oestrous cycle and pregnancy

Improving our understanding of the mechanisms controlling the corpus luteum (CL) and its role in regulating the reproductive cycle should lead to improvements in the sustainability of today's global animal industry. The corpus luteum (CL) is a transient endocrine organ composed of a heterogeneous mixture steroidogenic, endothelial and immune cells, and it is becoming clear that immune mechanisms play a key role in CL regulation especially in luteolysis. Toll‐like receptors (TLR) mediate innate immune mechanisms via the production of pro‐inflammatory cytokines, especially within various tissues, although the role of TLR within CL remains unknown. Thus, the objectives of this study were to characterize TLR mRNA expression in the CL during the oestrous cycle and in pregnancy (day 30–50), and to examine the role of TLR signalling in luteal cells. Corpora lutea were collected at various stages of the cycle and pregnancy and analysed for TLR and cytokine mRNA expression. In addition, luteal cells were cultured with the TLR4 ligand (lipopolysaccharide, LPS) for 24 h to evaluate the role of TLR4 in regulating luteal function. Toll‐like receptors 1, 2, 4, 6, tumour necrosis factor alpha (TNF), interferon gamma (IFN‐G), and interleukin (IL)‐12, mRNA expressions were greatest in regressing CL compared with earlier stages (p < .05), whereas no change was observed for IL‐6 mRNA expression. Cytokine mRNA expression in cultured luteal cells was not altered by LPS. Based on these data, one or more of the TLRs found within the CL may play a role in luteolysis, perhaps via pro‐inflammatory cytokine mRNA expression.     

奶山羊甘肃棘豆中毒卵巢,胎盘的病理学研究

为阐明甘肃棘豆引起山羊流产的机理，对９只怀孕关中奶山羊，每日按１０ｇ／ｋｇ体重剂量喂给甘肃棘豆粉。孕羊于第１０－４３ｄ陆续全部流产，流产的为弱羔、死胎、畸胎或腐败胎。流产羊子宫粘膜水肿、出血或腐败；母体胎盘整片出血或呈豆腐花状。光镜观察，卵卵巢黄体细胞、卵泡细胞和胎盘滋养层细胞胞浆广泛性空泡变性。透射电镜观察，卵母细胞、黄体细胞、合体滋养细胞的核仁和线粒体空泡变性；黄体细胞和合体滋养细胞核内出现不     

Effects of repeated administration of hCG on follicular and luteal characteristics and serum progesterone concentrations in eCG-superovulated Sanjabi ewes

The objective of this study was to evaluate if treatment of equine chorionic gonadotrophin (eCG)-superovulated Sanjabi ewes with repeated administration of human chorionic gonadotropin (hCG) would increase the number of normal corpus luteum (CL) and serum progesterone concentrations and decrease the number of persistent follicles. The superovulated ewes were divided into four groups on day 0 (day of sponge removal); the ewes were treated by an intramuscular administration of 500?IU hCG on day 0 (Group I: n?=?10), on days 0 and 1 (Group II: n?=?10), or on days 0, 1, and 2 (Group III: n?=?10) and no treatment for control group (n?=?10). Blood samples were collected on days 0, 1, 2, 5, and 8 (day of slaughter), and serum progesterone concentrations were determined. According to progesterone concentrations, 50 (4/8) and 0?% of the ewes underwent premature luteal regression in the control group and the hCG groups, respectively. There were more CLs in Group III than in Group II and the control group. Ewes treated with hCG had a greater number of normal-looking CL. CL diameter was significantly greater in Group II and Group III than other groups. Total CL weight was significantly (P?<?0.05) higher in Group III than in Group I and the control group. Number of persistent follicle and persistent follicle diameter were lower in control group compared to the other groups. Eight days after sponge removal, serum progesterone concentration was significantly higher in Group III than in Group I and the control group. The present results indicate that repeated administration of hCG supported CL formation, increased serum progesterone concentration, and prevented premature luteal regression in eCG-superovulated Sanjabi ewes.     

Ovarian function in ruminants

The purpose of this overview is to highlight important steps of ovarian regulation during follicle development, ovulation and the life span of corpus luteum (CL) in ruminants. The ovarian cycle is central to reproductive function. It is characterized by repeating patterns of cellular proliferation, differentiation and transformation that encompass follicular development and ovulation as well as the formation, function and regression of the CL. In the first part, the importance and regulation of final follicle growth and especially of angiogenesis and blood flow during folliculogenesis, dominant follicle development and CL formation are described. Our results underline the importance of growth factors especially of insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) for development and completion of a dense network of capillaries (angiogenesis) during follicle growth and CL formation. In the second part, the regulation of CL function by endocrine/paracrine and autocrine acting regulators is discussed. There is evidence that besides the main endocrine hormones luteinizing hormone (LH) and growth hormone (GH) local regulators as growth factors, peptides, steroids and prostaglandins are important modulators of luteal function. During early CL development until midluteal stage oxytocin (OT), prostaglandins and progesterone (P) itself stimulate luteal cell proliferation and function supported by the luteotropic action of a number of growth factors. The still high mRNA expression, protein concentration and localization of VEGF, FGF and IGF family members in the cytoplasm of luteal cells during midluteal stage suggest that they play pivotal role in the maintenance (survival) of this endocrine tissue. The major function of the CL is to secrete P. Progesterone itself regulates the length of the estrous cycle via influencing the timing of the luteolytic PGF2alpha signal from the endometrium. At the end of a nonfertile cycle, the regression of CL commences, steroidogenic capacity is lost (functional luteolysis), cell death is initiated, and tissue involution as well as resorption occurs within a few days (structural luteolysis). The cascade of mediators during luteolysis is very complex and still awaits elucidation. Evidence is given for participation of blood flow, inflammatory cytokines, vasoactive peptides (angiotensin II and endothelin-1), and decrease of the classical luteotropic mediators.