Miniature Ponies: Similarities and Differences from Larger Breeds in Follicles and Hormones during the Estrous Cycle

Recent direct and indirect comparisons between Miniature ponies and larger breeds during the estrous cycle are reviewed. There were many similarities but profound differences in the Miniature ponies, including (1) greatly reduced follicle population within each of several follicle diameter classifications, (2) smaller number of growing follicles 10 mm or larger per ovulatory wave (1.5 ± 0.3 vs. 5.8 ± 0.9 in Miniature ponies vs. horses), (3) lower incidence of detectable diameter deviation, (4) ovulatory luteinizing hormone (LH) surge that involved three distinct phases, and (5) LH increase and decrease during the early luteal phase that followed the ovulatory surge. Diameter of the preovulatory follicle was smaller in Miniature ponies than in horses, but the difference was slight (38 vs. 44 mm; 14%) when compared with an extreme difference in median body weight (123 vs. 465 kg; 74%). The great reduction in follicle population with only a slight reduction in diameter of the preovulatory follicle in Miniature ponies compared with larger breeds is an important consideration during both experimental and clinical examinations.     

Intrauterine infusion of BQ-610, an endothelin type A receptor antagonist, delays luteolysis in dairy heifers

Three separate in vivo experiments were conducted to evaluate the putative role of endothelin-1 (ET-1) during luteal regression in heifers. In Experiment 1, a single intraluteal injection of 500 μg BQ-610 [(N,N-hexamethylene) carbamoyl-Leu-d-Trp (CHO)-d-Trp], a highly specific endothelin A (ET_A) receptor antagonist, did not diminish the decline in plasma progesterone following a single exogenous injection of 25 mg prostaglandin F2 alpha (PGF₂) administered at midcycle of the estrous cycle. In Experiment 2, six intrauterine infusions of 500 μg BQ-610 given every 12 h on days 16–18 delayed spontaneous luteolysis, as evidenced by an extended elevation (P = 0.054) of plasma progesterone concentration. In Experiment 3, heifers were administered six intrauterine infusions of BQ-610 or saline on days 16–19, and peripheral blood samples were collected from day 11 to 16 (before infusion), hourly on days 16–19 (during infusion), and on days 20–25 (after infusion). BQ-610 treated heifers had markedly higher (P < 0.0001) levels of plasma progesterone compared with saline controls, and this effect was most notable during the infusion period (treatment by period interaction; P ≤ 0.05). Heifers infused with BQ-610 also had higher progesterone levels on day 21 (treatment by time interaction; P ≤ 0.05). Mean plasma concentrations of 13,14-dihydro-15-keto-PGF₂ (PGFM), the primary metabolite of PGF₂, were measured in the samples collected hourly and were not different (P ≥ 0.05) between treatments. These results indicate that the in vivo antagonism of the ET_A receptor can delay functional luteolysis, and supports the theory that ET-1 regulates luteal function in ruminants.     

牦牛不同妊娠阶段孕酮的主要来源器官研究

为明确牦牛不同妊娠阶段孕酮的来源，分别对53头不同妊娠阶段牦牛的黄体组织、肾上腺组织和胎盘组织进行体外细胞培养，同时对44头牦牛的上述组织进行匀浆处理，采用放射免疫分析法（RIA）测定培养液及组织匀浆上清液中孕酮的含量。结果显示，黄体细胞在体外培养时，妊娠前2个月内孕酮分泌量显著升高（P〈0．05）：妊娠2-5个月，培养液中孕酮含量变化不明显（P〉0．05），但在妊娠5个月以后，其浓度又开始显著增加（P〈0．01）。肾上腺组织体外培养时，分泌孕酮的能力随不同个体差别较大，孕酮浓度在整个妊娠期变化不明显（P〉0．05）。胎盘组织体外培养时仅分泌少量孕酮，且在整个妊娠期其浓度变化不明显。黄体组织匀浆上清液中孕酮浓度在妊娠前2个月内呈上升趋势（P〈0．05），之后其浓度开始下降，至妊娠第4个月时下降到最低水平，以后又逐渐上升（P〈0．05），妊娠6-7个月时达到峰值，临近分娩时，又下降至较低水平。肾上腺组织匀浆中孕酮含量的变化差异较大，且无明显的变化趋势，胎盘组织匀浆中孕酮的含量也很低，甚至检测不到。结果表明，黄体是牦牛整个妊娠期孕酮的主要来源器官。     

黄体机能与生长因子关系的研究进展

论述了黄体的形成和机能 ,同时介绍了EGF、TGF、IGF和VEGF等生长因子对黄体的调控作用     

前列腺素D2与F2α对绵羊黄体退化的影响及其机理研究

旨在研究前列腺素（prostaglandins,PGs）D₂与F_2α对绵羊黄体（corpus luteum,CL）组织形态、生殖激素及其关键基因与受体表达的影响,并解析其在黄体退化中的相互关系及机理,为保证母畜连续性繁育提供新的理论依据。将16只哈萨克绵羊随机分成4组,在发情周期的黄体期分别子宫肌内注射PGD₂、PGF_2α、PGD₂+PGF_2α及等量生理盐水（对照组）,采用HE染色结合物理拍照对比处理前后黄体组织形态变化,ELISA法检测外周血清中P₄、E₂、PGD₂和PGF_2α浓度变化;并利用qRT-PCR和Western blot检测关键合成酶基因HPGDS、PGFS及其受体DP1、CRTH2、FP的mRNA和蛋白表达水平。结果显示,与对照组相比,发现PGD₂+PGF_2α组中黄体退化效果最明显,随后依次是PGF_2α组明显大于PGD₂组。ELISA结果显示,随着处理后时间的推移,不同试验处理组中,P₄浓度均呈显著下降趋势（P<0.05）,其中在PGD₂+PGF_2α组中该变化趋势最显著（P<0.05）;但E₂、PGD₂和PGF_2α浓度均呈现不同差异性变化,其中,PGD₂+PGF_2α组中PGD₂和PGF_2α浓度呈显著下降（P<0.05）,PGF_2α组中E₂浓度呈显著升高（P<0.05）、PGD₂浓度呈显著下降（P<0.05）,PGD₂组中E₂浓度呈显著下降趋势（P<0.05）、PGD₂浓度呈显著升高趋势（P<0.05）。qRT-PCR和Western blot结果显示,与对照组相比,PGD₂+PGF_2α组中HPGDS mRNA和蛋白表达量显著下调（P<0.05）,PGFS、CRTH2及FP mRNA和蛋白表达量显著上调（P<0.05）;PGF_2α组中HPGDS mRNA和蛋白表达量呈显著下调（P<0.05）,其它基因mRNA和蛋白表达量呈显著上调（P<0.05）;PGD₂组中HPGDS、DP1、PGFS及FP mRNA和蛋白表达量呈显著上调（P<0.05）。同时,在不同受体基因表达量检测时,发现PGD₂组中DP1受体表达量显著高于CRTH2受体（P<0.05）,而PGF_2α组中CRTH2表达量则显著高于DP1（P<0.05）。综上,PGD₂无论单独使用还是结合PGF_2α使用,均能够促进CL的退化,尤其是二者结合时有明显的协同促溶效应,其作用机制可能与其体内激素水平、关键合成酶及受体类型的表达有关,这为全面认识哺乳动物CL退化的调控机制奠定了基础,也为进一步优化高效繁殖技术（尤其是PGs方案）提供了新的思路。     

牦牛发情周期黄体组织结构的观察

选用48头成年母牦牛，采用光镜和电镜技术对发情周期中不同时期黄体的组织结构进行了观察。结果表明，牦牛黄体主要由2种细胞组成，即颗粒黄体细胞（granulasa lutein cell，GLC）和膜黄体细胞（theca lutein cell，TLC），其特征性变化主要表现在GLC和纤维的分布。成熟黄体中GLC及其胞核的平均直径分别为36．6μm和15．2μm，而TLC则分别为14．4μm和10．9μm。黄体细胞胞质中线粒体的比例随黄体的成熟而增高；脂滴在Ⅰ期黄体时较多，Ⅱ期时减少，Ⅲ期时显著增多，后又减少；滑面内质网也随黄体的成熟而增加，并随黄体的退化发生膨胀。黄体组织中有同心圆状或同心轮状的粗面内质网膜系统。黄体细胞间主要是缝隙连接，偶见中间连接。黄体组织中存在窗孔型毛细血管．     

牛卵巢黄体类型与闭锁卵泡之间关系的探讨

通过对牛卵巢不同黄体类型和闭锁卵泡的组织学研究 ,探讨了不同黄体类型与闭锁卵泡数量和直径之间的关系。试验结果表明牛卵巢黄体类型其功能强弱不同直接影响正在闭锁、近完全闭锁和完全闭锁卵泡的数量和直径     

奶山羊妊娠黄体中催产素免疫反应细胞的分布

运用免疫组化ABC法妊娠26～120d的奶山羊黄体中催产素免疫反应细胞的分布进行了观察。结果表明，奶山羊妊娠黄体中存在催产素(Oxytocin,OT）免疫反应阳性细胞。阳性细胞在形态上以卵圆形、圆形、棱形为主，还有一些具有明显的突起。根据阳性细胞胞质内反应颗粒着色的深浅，可把OT阳性细胞分为强阳性、中等阳性和弱阳性3种。在妊娠26～30d，阳性细胞数量最多，强阳性细胞主要分布于黄体的周边，中等阳性及弱阳性细胞则均匀分布于整个黄体组织中，妊娠31～60d，阳性细胞数量明显下降，弥散于整个黄体组织中；妊娠61～120d，阳性细胞的数量及逐渐增多，以中等阳性和弱阳性细胞为主，而强阳性细胞数量较少。连续切片HE染色的对照观察显示妊娠黄体中大、小黄体细胞均可出现OT免疫阳性反应。     

新疆细毛羊超数排卵效果研究

[目的]提高并稳定新疆细毛羊超数排卵效率,为以生产2~8-细胞期胚胎的转基因研究提供素材.[方法]分别从激素生产厂家、供体年龄、激素处理方案等3个方面探讨新疆细毛羊的超数排卵效果,确定新疆细毛羊超数排卵供体羊的最佳年龄及其有效处理方案.[结果]不同生产厂家的激素对新疆细毛羊黄体数和可用胚胎数均存在极显著影响(P<0.01):1.5周岁以内的新疆细毛羊超排后,其黄体数(6.17个/只)和可用胚胎数(1.50枚/只)均极显著低于2.0周岁以上的新疆细毛羊(黄体数12.24个/只,可用胚胎数8.30枚/只)(P<0.01);FSH剂量在150~200 U/只范围内不影响超排效果和胚胎质量( P>0.05):FSH+PMSG超排处理的新疆细毛羊黄体数(6.05个/只)和可用胚胎数(1.76枚/只)则显著低于FSH+PG超排处理(黄体数17.11个/只,可用胚胎数10.38枚/只)(P<0.01).[结论]新疆细毛羊超数排卵时宜选用2.0周岁以上的供体羊,FSH剂量控制在150~200 U/只,若能与PG联合使用其超排效果更好,但不宜与PMSG联合使用.     

Expression of prostaglandin F(2α) (PGF(2α)) receptor and its isoforms in the bovine corpus luteum during the estrous cycle and PGF(2α)-induced luteolysis

Prostaglandin F(2α) (PGF(2α)) induces luteolysis via a specific receptor, PTGFR. Although PTGFR mRNA expression in the bovine corpus luteum (CL) has been studied previously, changes in PTGFR protein and its localization are not fully understood during the life span of the CL. In addition to full-length PTGFR, several types of PTGFR isoforms, such as PTGFRα (type I) and PTGFRζ (type II), were reported in the bovine CL, suggesting isoform-specific luteal action. Full-length PTGFR mRNA in the bovine CL increased from the early to the mid-luteal phase and decreased during luteolysis, whereas PTGFR protein remained stable. PTGFR protein was localized to both luteal and endothelial cells and was expressed similarly during the life span of the CL. Like full-length PTGFR mRNA, PTGFRα and PTGFRζ mRNA also increased from the early to mid-luteal phases, and mRNA of PTGFRζ, but not PTGFRα, decreased in the regressing CL. During PGF(2α)-induced luteolysis, the mRNAs of full-length PTGFR, PTGFR,α and PTGFRζ decreased rapidly (from 5 or 15 min after PGF(2α) injection), but PTGFR protein decreased only 12 h later. Silencing full-length PTGFR using small interfering RNA prevented PGF(2α)-stimulated cyclooxygenase-2 (PTGS2) mRNA induction. By contrast, PGF(2α) could stimulate vascular endothelial growth factor A (VEGFA) mRNA even when full-length PTGFR was knocked down, thus suggesting that PGF(2α) may stimulate PTGS2 via full-length PTGFR, whereas VEGFA is stimulated via other PTGFR isoforms. Collectively, PTGFR protein was expressed continually in the bovine CL during the estrous cycle, implying that PGF(2α) could function throughout this period. Additionally, the bovine CL expresses different PTGFR isoforms, and thus PGF(2α) may have different effects when acting via full-length PTGFR or via PTGFR isoforms.