超排山羊卵巢卵母细胞体外成熟和体外受精的研究

以ＴＣＭ１９９＋１０ｍｍｏｌ／ＬＨＥＰＥＳ＋青霉素（６ｍｇ／Ｌ）＋链霉素（５ｍｇ／Ｌ）为基础培养液（ＢＭ），再分别加入不同成分，配成５种卵母细胞成熟液：（Ａ）ＢＭ＋１０％ＥＧＳ；（Ｂ）ＢＭ＋１０％ＥＧＳ＋ＨＣＧ（２．５ｍｇ／Ｌ）；（Ｃ）ＢＭ＋１０％ＥＧＳ＋ＨＣＧ＋Ｅ２（１ｍｇ／Ｌ）；（Ｄ）ＢＭ＋１０％ＦＣＳ＋ＨＣＧ＋Ｅ２；（Ｅ）ＢＭ＋１０％ＥＧＳ＋ＨＣＧ＋Ｅ２＋颗粒细胞（１．５×１０６～３．０×１０６个／ｍＬ）。在３８．５℃、５％ＣＯ２下培养２６ｈ，排卵后第１天卵巢卵母细胞体外成熟率分别为６７．６７％（２０／３０），６０．４２％（２９／４８），８３．６７％（４１／４９）和８０．８２％（５９／７３），排卵后第５天卵巢卵母细胞，在培液Ｄ中体外成熟率为７１．４３％（４５／６３）。排卵后第１天的９８枚卵巢卵母细胞，体外成熟体外受精卵裂率为２１．４３％，２１枚２细胞胚移植５头受体获２头羔羊。研究表明，超排山羊卵巢卵母细胞经体外成熟可获得大量廉价的成熟卵母细胞，并可通过体外受精获得试管山羊     

仔猪断奶应激对血液和生化的影响

随机选取 １０ 头健康的４２～４５ 天断奶长白仔猪,分别于断奶时、断奶后７ 天、１４ 天上午采血,检验血液学、血清生化等多项指标,结果如下：仔猪血清 Ａ Ｓ Ｔ、 Ｃ Ｋ、 Ｌ Ｄ Ｈ 活性在断奶后 ７ 天时都升高,其中 Ａ Ｓ Ｔ、 Ｌ Ｄ Ｈ活性与断奶时相比差异极显著（ Ｐ＜ ００１）;血清 Ａ Ｍ Ｙ Ｌ 活性,断奶后均比断奶时高,但无统计学上差异（ Ｐ＞００５）;血清 Ｔ Ｐ、 Ｇ Ｌ Ｏ Ｂ、 Ａ Ｌ Ｂ、 Ｂ Ｕ Ｎ、 Ｃ Ｈ Ｏ Ｌ 含量在断奶后极显著或显著降低（ Ｐ＜ ００１ 或 Ｐ＜ ００５）; Ｇ Ｌ Ｕ、 Ｃ Ｒ Ｅ Ａ、 Ｔ Ｃ Ｏ２ 含量降低,但无统计学上差异（ Ｐ＞ ００５）。血液 Ｒ Ｂ Ｃ、 Ｈ Ｇ Ｂ、 Ｈ Ｃ Ｔ、 Ｍ Ｃ Ｖ 断奶后极显著降低（ Ｐ＜００１）, Ｍ Ｃ Ｈ Ｃ 断奶后极显著升高（ Ｐ＜ ００１）; Ｗ Ｂ Ｃ、 Ｐ Ｌ Ｔ 等断奶后虽有变化,但均无统计学上差异（ Ｐ＞００５）。结果表明,仔猪在断奶后一段时间,处于营养缺乏性单纯小红细胞性贫血状态。     

次黄嘌呤对猪卵母细胞体外自发成熟抑制作用的研究

利用猪卵母细胞体外无血清培养技术,研究了次黄嘌呤（ＨＸ）对猪卵母细胞体外自发成熟的抑制作用。猪卵丘－卵组细胞复合体（ＣＯＣ）和裸卵母细胞（ＤＯ）取自初情期猪卵巢,培养在Ｍ－１９９培养液中,并施以各种自理培养不同时间后,观察卵母细胞核成熟（ＧＶＢＤ）情况。实验结果表明：⑴ＨＸ（１－４mmol/Ｌ）对猪ＣＯＣ的自发成熟具有抑制 作用,且具有剂量领事关系。４mmol/Ｌ的ＨＸ对ＣＯＣ和ＤＯ自发成熟的抑制作用,且具     

牛体外受精胚胎细胞核移植的实验研究

将采自肉联厂屠宰车间的牛卵巢中的卵母细胞置于ＴＣＭ－１９９＋１０％ＥＣＳ（０ｄ）＋ＦＳＨ（１万ＩＵ／Ｌ）＋ＬＨ（５ｍｇ／Ｌ）中培养成熟，用含０．３％透明质酸酶的消化液将卵母细胞周围的卵丘细胞去掉，并以７．５ｍｇ／Ｌ的ＣＢ液处理后，用微吸管吸去透明带内的第一极体及极体下面的部分卵母细胞质，然后将经体外受精并发育至８～１６细胞期胚胎的卵裂球注入去核卵母细胞的卵周隙中，再将移核胚置于电融合槽内进行融合（电场强度为１２００Ｖ／ｃｍ，持续时间为８０μｓ，１次脉冲刺激）。将融合的胚胎移入生长有单层贴壁颗粒细胞的发育培养液（ＴＣＭ－１９９＋１０％牛血清）中培养，观察移核胚的融合率及发育率，部分去核卵母细胞经染色后观察去核率。结果表明：（１）移核胚的融合率为８６．９％（５３／６１）；（２）发育至２～８细胞期的胚胎占培养的移核胚胎总数的２１．３％（１０／４７）；（３）卵母细胞的去核率为６８．２％（４５／６６）。     

不同月龄鸵鸟38项血液生化参数比较

比较了 １～３ 月龄（ ｎ ＝ １５）和 ４～６ 月龄（ ｎ ＝ １５）鸵鸟血液的 ３８ 项生化参数。结果，１～３ 月龄和 ４～６ 月龄鸵鸟之间血清 Ｃ Ｋ、 Ｔ Ｇ、 Ｂ Ｕ Ｎ、 Ｂ Ｕ Ｎ／ Ｃ Ｒ Ｅ、 Ｕ Ａ、 Ｍ ｇ、 Ｐ含量差异极显著（ Ｐ ＜ ００１）；血清 Ｔ Ｂ Ａ、 Ｌ Ｄ Ｌ Ｃ、 Ｃ Ｈ Ｏ、 Ｔ Ｔ Ｔ、 Ｎａ、 Ｋ 含量的组间差异显著（ Ｐ ＜ ００５）；其他指标 ２ 组间差异不显著。该结果提示，不同月龄鸵鸟的营养物质代谢过程存在一定差异。     

三至七月龄小尾寒羊营养代谢中甲烷气产量和能值的初步研究

取３月龄断奶小尾寒羊９只随机分为３组（每组１只去势公羊，２只母羊）进行气体能量代谢试验。试验表明，日粮代谢能浓度为２３００～２７００ｋｃａｌ／ｋｇＤＭ、食入代谢能２６００～４８００ｋｃａｌ／ｋｇＤＭ时，甲烷气（ＣＨ４）呼出量２４～３３Ｌ／ｄ，ＣＨ４能（ＣＨ４Ｅ）２２０～３１０ｋｃａｌ／ｄ，甲烷能占食入总能的６％～９％，呼出气体甲烷浓度约为０１０％～０１７％。甲烷能与食入总能回归关系为：３～５月龄：ＣＨ４呼出量（Ｌ／ｄ）＝８７１０６＋０００５２ｘ；ＣＨ４Ｅ（ｋｃａｌ／ｄ）＝７８９７２７＋００５００ｘ；ＣＨ４Ｅ／ＧＥＩ（％）＝１０１５０４－００００８ｘ。５～７月龄：ＣＨ４呼出量（Ｌ／ｄ）＝１１５２１５＋０００４５ｘ；ＣＨ４Ｅ（ｋｃａｌ／ｄ）＝１０８８８３０＋００４２８ｘ；ＣＨ４Ｅ／ＧＥＩ（％）＝１１９４４１－０００１２ｘ。     

海狸鼠卵母细胞体外成熟培养初探

实验用ＰＭＳＧ或ＰＭＳＧ＋ＨＣＧ处理或未经激素处理的海狸鼠８只，共获卵巢卵母细胞１３８枚。激素处理对获取卵巢卵母细胞的数量没有影响，而对体外成熟发育至卵丘扩展和半成熟阶段有促进作用。三种不同培养液（Ｗｈｉｔｅｎ＋ＦＣＳ；ＴＣＭ１９９＋ＰＭＳＧ＋ＦＣＳ；ＴＣＭ１９９＋ＨＣＧ＋ＦＣＳ）共培养１２５枚卵母细胞，培养后卵丘扩展率及半成熟率分别为５６．５％，４５．７％，４７．６％和２１．７％，１２．３％，９．５％，以Ｗｈｉｔｅｎ液较高（分别为５６．５％和２１．７％），但只有ＴＣＭ１９９＋ＰＭＳＧ＋ＦＣＳ组有２枚卵母细胞出现第一极体。结果表明海狸鼠卵母细胞与其它啮齿动物的卵母细胞一样，能够在体外培养成熟，完成第一次减数分裂，排出第一极体     

SPF鸡人工感染鸡败血霉形体后血液生物化学变化

用鸡败血霉形体（ＭＧ）国际标准强毒Ｒ株人工感染１５日龄ＳＰＦ鸡,在感染后１５ｄ采血作血液生物化学检验。结果：ＴＢｉｌ、ＧＯＴ、ＧＰＴ、ＡＬＰ、ＬＤｈ、ＣＯ２－ＣＰ、ＣＲＥ、ＢｕＮ、ＣＲＥ－Ｕ、无机磷、Ｍｇ＾２＋明显升高,而ＴＰ、ＡＬＢ、Ａ／Ｇ、Ｃｈｏ、Ｇｌｕ、Ｃａ＾２＋等明显下降,ＲＢＣ和Ｈｂ下降,ＷＢＣ上升,其中ＬＣ和嗜酸性白细胞明显上升。说明ＭＧ不仅造成呼吸系统障碍,也对肝功能和功能产生较大影     

猪Y染色体上存在人PY3.4同源顺序的初步证据

猪Ｙ染色体上存在人ＰＹ３．４同源顺序的初步证据ＴＨＥＰＲＩＭＡＲＹＥＶＩＤＥＮＣＥＯＮＴＨＥＨＯＭＯＬＧＵＥＴＯＰＹ３．４ＤＮＡＦＲＡＧＭＥＮＴＳＲＥＳＩＤＩＮＧＩＮＴＨＥＹＣＨＲＯＭＯＳＯＭＥＯＦＰＬＧＳ李奎，蒋建桥，沈亦平，张木先，张锡元ＬｉＫｕ...     

鸡糖皮质激素受体阻断模型的建立

采用药物缓释法，给雏鸡皮下注射糖皮质激素（ＧＣ）拮抗剂ＲＵ４８６（５０ｍｇ／ｋｇ），经放射蛋白分析法测得血浆ＲＵ４８６含量可达（２３７．２±８．７４）ｎｍｏｌ／Ｌ，并在该水平上维持３０ｈ；血浆总ＧＣ浓度为（１３８．３±１１．４５）ｎｍｏｌ／Ｌ，较对照雏鸡虽有所升高，但始终低于有效期内血浆ＲＵ４８６水平。在此期间，雏鸡外周血淋巴细胞糖皮质激素受体（ＧＲ）阻断率达６１．５８％±３．４２％，血浆磷脂酶Ａ２未见变化，外周血淋巴细胞程序性死亡减少。从而成功地建立了雏鸡ＧＲ阻断模型，并可维持２４ｈ。给模型雏鸡注射外源性皮质酮，结果显示，雏鸡能有效地抵抗高水平血浆皮质酮的作用     

Effects of adding luteinizing hormone to a medium containing follicle stimulating hormone on progesterone-induced differentiation of cumulus cells during meiotic resumption of porcine oocytes

In the present study, we investigated the effects of adding luteinizing hormone (LH) to a medium containing follicle stimulating hormone (FSH) on the shift in expression of progesterone receptor (PR) isoforms (PR‐A and PR‐B) and the roles in function of cumulus cells of cumulus‐oocyte complexes (COC). The level of PR‐B mRNA in cumulus cells was up‐regulated by FSH during the first 16‐h cultivation but the level was significantly decreased at 20 h. The decrease of PR‐B mRNA was accelerated when COC were cultured with FSH and LH. Still, a high level of total PR mRNA was maintained in cumulus cells cultured with or without the addition of LH up to 20 h, suggesting that the expression of PR isoforms was shifted from PR‐B to PR‐A in cumulus cells. The reduction of PR‐B was also induced by addition of progesterone to FSH‐containing medium. The addition of LH or progesterone to FSH‐containing medium stimulated cumulus expansion of COC as compared with that of COC cultured with FSH. In the expanded COC, ADAMTS‐1 which is expressed in granulosa cells and cumulus cells in rodent follicles through LH‐induced progesterone‐ and PR‐dependent pathway, was more accumulated within the COC matrix. These results suggest that the addition of LH or progesterone to FSH‐containing medium is required for the differentiation of cumulus cells, such as cumulus expansion, mediated by the shift from PR‐B to PR‐A in them.     

Effects of FSH and LH on Steroid Production by Buffalo (Bubalus bubalis) Granulosa Cells Cultured In Vitro Under Serum‐Free Conditions

The objective of this study was to examine the effects of FSH and LH on oestradiol‐17β and progesterone production by buffalo granulosa cells cultured under serum‐free conditions. Granulosa cells (3 × 10⁵) from small (≤5 mm diameter) follicles were cultured for up to 4 days in 48‐well plates coated with 3.3 μg/cm² fibronectin in Dulbecco's modified Eagle's medium (DMEM) : nutrient mixture F‐12 Ham (1 : 1 ratio) supplemented with 10^?7 m androstenedione, 5 μg/ml human apo‐transferrin and 0.1% bovine serum albumin, in the presence or absence of FSH or LH (0, 1, 2, 4, 8, 16, 32 or 64 ng/ml each). Basal oestradiol‐17β production by granulosa cells from small follicles reduced (p < 0.01) from days 1 to 2 of culture and became undetectable by day 3 and basal progesterone production increased (p < 0.05) from day 1 through day 4 of the culture. Although there was no effect of FSH on day 1 of the culture, FSH at 2, 4, 8 and 16 ng/ml increased (p < 0.05) oestradiol‐17β production by granulosa cells from small follicles on day 2. Progesterone secretion was increased (p < 0.05) by all doses of FSH on all days of culture. All doses of LH had no effect on oestradiol‐17β or progesterone production by granulosa cells from small follicles on any day of the culture. The results of this study demonstrate a serum‐free culture system for buffalo granulosa cells and stimulatory effect of FSH but not LH on steroid hormone production by buffalo granulosa cells under these conditions.     

Effects of exogenous insulin and body condition on metabolic hormones and gonadotropin-induced follicular development in prepuberal gilts

To determine influences of insulin and body condition on follicular growth, prepuberal gilts (n = 16) treated with pregnant mare's serum gonadotropin (PMSG) were used in a 2 X 2 factorial experiment with main effects of insulin (0 or .4 IU/kg every 12 h beginning at 1800 on the day before PMSG) and backfat depth (moderate, 25 +/- .8; high, 32 +/- .7 mm; P less than .0001). Body weights were similar. Blood sampling was at 6-h intervals for analyses of LH, FSH, growth hormone (GH), glucagon, cortisol, insulin, insulin-like growth factor-I (IGF-I), plasma urea nitrogen (PUN), nonesterified fatty acids (NEFA), testosterone, estradiol-17 beta, and progesterone. Ovaries were removed 75 h after PMSG treatment, and visible small (less than or equal to 3 mm), medium (4 to 6 mm), large (greater than or equal to 7 mm), and macroscopically atretic follicles were counted. Administration of insulin increased IGF-I in fluid of medium follicles (108.8 vs 60.7 ng/ml; SEM = 13.3; P less than .05). Neither insulin nor fatness affected hCG binding by granulosa cells (12.5 +/- 1.6 ng/10(6) cells) or numbers of large (16.7 +/- 2.6) and medium (10.4 +/- 2.3) follicles. However, insulin increased the number of small follicles (58.9 vs 29.9; SEM = 9.7; P less than .05) and reduced the number of atretic follicles (3.8 vs 11.3; SEM = 1.1; P less than .05). The predominant effect of insulin on reducing number of atretic follicles was in the small size class (.6 vs 6.9; SEM = .6, P less than .01). Follicular fluid estradiol and progesterone were not affected by treatments; however, testosterone concentrations in large follicles were lower in gilts with higher backfat (32.5 vs 59.9 ng/ml; SEM = 4.0; P less than .05). Systemic LH, FSH, glucagon, cortisol, PUN, NEFA, estradiol, and testosterone were not affected by insulin or level of feeding. However, GH was lower in gilts that had higher backfat (overall average of 3.2 vs 2.8 ng/ml; SEM = .1; P less than .05). Insulin reduced atresia and altered intrafollicular IGF-I independently of body condition and without sustained effects on other hormones.     

Development of a culture system for bovine granulosa cells: effects of growth hormone, estradiol, and gonadotropins on cell proliferation, steroidogenesis, and protein synthesis

The objectives of the present studies were 1) to develop a culture system that has the positive effect of serum on granulosa cell attachment and allows subsequent expression of hormonal effects in serum-free medium and 2) to determine the effect of insulin, epidermal growth factor (EGF), estradiol (E2), and growth hormone (GH) on growth, steroidogenesis, and(or) protein synthesis of bovine granulosa cells. Cells from small (1 to 5 mm) and large (greater than 8 mm) follicles were collected from cattle and cultured for either 4 or 6 d. When cells from small follicles were cultured, insulin (5 micrograms/ml) increased (P less than .05) cell numbers (cells x 10(5)/well) severalfold compared with controls. Alone, EGF (10 ng/ml), FSH (200 ng/ml), LH (200 ng/ml), E2 (2 micrograms/ml), or GH (0 to 1,000 ng/ml) had no effect on cell numbers. However, when included with insulin, 30, 100, and 300 ng/ml of GH increased (P less than .05) granulosa cell numbers on d 4 of culture. Insulin alone increased (P less than .05) progesterone production (ng.10(5) cells-1.24 h-1) by severalfold on d 4, but EGF, FSH, LH, or GH alone had no effect and E2 inhibited progesterone production. In the presence of insulin, FSH and GH (100 ng/ml) increased (P less than .05) progesterone production on d 4 of culture, whereas EGF (10 ng/ml) elicited a decrease (P less than .05) in production. In cells from both sizes of follicles, GH (300 ng/ml) increased synthesis of cellular proteins (greater than 10 kDa). In cells from only large follicles, LH (200 ng/ml) decreased synthesis and secretion of proteins (greater than or equal to 3.5 kDa). These results support the hypothesis that GH may have direct effects on bovine ovarian function.     

褪黑素对体外培养绵羊垂体细胞分泌FSH和LH的影响

本文采用体外细胞培养和放射免疫测定法(RIA)的方法,研究了褪黑素(MLT)对季节性繁殖的蒙古母羊垂体细胞分泌促卵泡素(FSH)和促黄体素(LH)的作用。结果表明:当单独用递增的MLT(10、100、1000、2000pg/mL)处理原代垂体细胞时,随时间的延长FSH的分泌量极显著下降(P<0.01),但对LH的基础分泌没有影响;无论用10IU/mLhCG单独刺激,还是用不同剂量MLT与10IU/mLhCG共同刺激垂体细胞,FSH和LH的分泌都极显著高于对照组(P<0.01),但与MLT的剂量没有关系。     

培养介质、卵丘细胞和卵泡直径对猪卵母细胞体外成熟的影响

A类卵母细胞在mTCM 199、NCSU2 3和NCSU37体系中培养 4 4～ 5 2小时后 ,成熟率分别为 76 .1%、78.1%和 6 5 .2 %。前两者差异不显著 (P >0 .0 5 ) ,但显著高于后者 (P <0 .0 5 )。卵母细胞在添加eCG和hCG的NCSU2 3体系中的成熟率 (75 .6 % )明显高于添加FSH的LH和成熟率 (6 5 .2 % ) (P <0 .0 5 )。A、B、C三类卵母细胞在NCSU2 3的成熟率分别为 73.3%、6 0 .4 %和 11.0 % ,三者间差异显著 (P <0 .0 5 )。大 (ф >6mm)、中 (ф =3～ 6mm)和小 (ф <3mm)三种卵泡中的卵母细胞在NCSU2 3中培养后 ,成熟率分别为 5 6 .2 % ,78.1%和 5 1.9% ,中等卵泡中卵母胞的体外成熟率显著高于其他两组 (P <0 .0 5 )。     

屠宰绵羊卵巢卵母细胞的体外培养

为了使屠宰绵羊卵巢卵母细胞能够用于体外受精,本文着重探索了使卵巢卵母细胞体外培养成熟的方法和条件。实验结果表明,以TCM-199加10％FCS作为基本培养基,培养24～25小时,可以使绵羊卵巢卵母细胞培养成熟,其成熟率可达55.5％(435/784)。如果在培养液内添加hCG(0.02mg/ml)或LH(0.01mg/ml),并且尽可能保持卵丘细胞的完整,则可以使成熟率提高到76.9％(140/182)～82.9％(112/135)。     

Follicle-stimulating hormone and luteinizing hormone regulate the synthesis mechanism of dihydrotestosterone in sheep granulosa cells

Steroid hormones and receptors play important roles in female reproduction, and their expression patterns affect follicular growth and development. To examine the expression of dihydrotestosterone (DHT) synthases (5α-reductases (5α-red1 and 5α-red2)) and androgen receptor (AR) during follicular development, and the regulation of DHT signalling by follicle-stimulating hormone (FSH) and luteinizing hormone (LH), we have used enzyme-linked immunosorbent assays, quantitative real-time polymerase chain reaction, immunohistochemical staining and Western blotting to examine DHT synthesis in small (≤2 mm), medium (2–5 mm) and large (≥5 mm) sheep follicles. Expression of 5α-red1, 5α-red2 and AR was observed in ovine ovaries, and with the development of follicles, the expressions of 5α-red1 and 5α-red2 mRNA and protein increased, but the levels of AR mRNA, protein and DHT level decreased. In addition, granulosa cells were treated with FSH (0.01, 0.1 and 1 international unit (IU)/ml), LH (0.01, 0.1 and 1 IU/ml) and testosterone (T, 10^–7 M) to evaluate the effects of FSH and LH on DHT and oestradiol (E2) synthesis and 5α-red1, 5α-red2 and AR expression. We found that FSH and LH upregulated 5α-red1 and 5α-red2 in sheep granulosa cells, but downregulated the concentration of DHT and expression of AR. Meanwhile, FSH and LH significantly upregulated the expression of aromatase (P450arom) and secretion of E2. This result indicates that although FSH and LH promote the expression of 5α-red1 and 5α-red2, T is not transformed into DHT, but E2. This study reveals the reason why DHT concentration is downregulated in large follicles and lays a foundation for further exploring the synthesis mechanism of DHT during follicular development.     

Influence of gonadotropins on insulin- and insulin-like growth factor-I (IGF-I)-induced steroid production by bovine granulosa cells

To determine the effect of gonadotropins on insulin- and insulin-like growth factor (IGF-I)-induced bovine granulosa cell functions, granulosa cells from bovine ovarian follicles were cultured for 2 days in the presence of 10% fetal calf serum (FCS), and then cultured for an additional 2 days in serum-free medium with added hormones. In the presence of 0 or 1 ng/mL of insulin or IGF-I, FSH had little or no effect (P>0.05) on estradiol production by granulosa cells from both small (1–5 mm) and large (≥8 mm) follicles. However, in the presence of ≥3 ng/mL of insulin, FSH increased (P<0.05) estradiol production by granulosa cells from small and large follicles such that the estimated dose (ED₅₀) of insulin necessary to stimulate 50% of the maximum estradiol production was decreased by 2- to 3-fold from 22 to 28 ng/mL in the absence of FSH to 7–14 ng/mL in the presence of FSH. Similarly, in the presence of ≥3 ng/mL of IGF-I, FSH increased (P<0.05) estradiol production by granulosa cells from small and large follicles such that the ED₅₀ of IGF-I for estradiol production was decreased by 4- to 5-fold from 25 to 36 ng/mL in the absence of FSH to 5–6 ng/mL in the presence of FSH. In the presence of FSH, the maximal effect of insulin on estradiol production was much greater than that of IGF-I (137- versus 12-fold increase) and were not additive; when combined, 100 ng/mL of IGF-I completely blocked the stimulatory effect of 100 ng/mL of insulin. In the absence of FSH, the maximal effect of insulin and IGF-I on estradiol production was similar. Concomitant treatment with 30 ng/mL of LH reduced (P<0.05) insulin-stimulated estradiol production by 52% on day 1 and 19% on day 2 of treatment. Insulin, IGF-I and FSH also increased (P<0.05) granulosa cell numbers and progesterone production but their maximal effects were less (i.e., <4-fold increase) than their effects on estradiol production. In conclusion, insulin and IGF-I synergize with FSH to directly regulate ovarian follicular function in cattle, particularly granulosa cell aromatase activity.     

Follicular growth and production of estrogen and progesterone after injection of gilts with human chorionic gonadotropin on day 12 of the estrous cycle

Twenty cyclic gilts were injected im with either saline (control) or 1,000 IU of human chorionic gonadotropin (hCG) on d 12 of the estrous cycle to determine the effects of hCG on follicular development and steroidogenesis. Blood was collected when gilts were sacrificed on d 13 or 16. Follicles were classified as medium (3 to 6 mm in diameter) or large (greater than 6 mm diameter), dissected from the ovary, measured and weighed. Pieces of follicle wall were incubated 3 h in Krebs Ringer bicarbonate buffer (KRB) on ice in an atmosphere of air or at 37 C in an atmosphere of 95% O2:5% CO2. Unconjugated estrogen and progesterone in blood plasma, follicular fluid and 10,000 X g supernatants of incubated follicular tissue homogenates were quantified by radioimmunoassay. On d 13 follicles on ovaries of control or hCG-injected gilts were less than or equal to 6 mm in diameter. On d 16, one of five control gilts had some large follicles, while all five hCG-treated gilts had large as well as medium follicles. On d 16 follicular fluid of large follicles from hCG-injected gilts contained twofold more estrogen and 40-fold more progesterone than medium follicles on the same ovaries. Tissue from large follicles of hCG-injected gilts produced more progesterone in vitro than did tissue from medium follicles (P less than .05), but estrogen production did not differ. On d 16 medium follicles from control or hCG-injected gilts were larger, contained more estrogen and less progesterone than those recovered on d 13 (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)