Effect of dominant follicle persistence on follicular fluid oestradiol and inhibin and on oocyte maturation in heifers
Effect of dominant follicle persistence on follicular fluid oestradiol and inhibin and on oocyte maturation in heifers
复制标题
DOI：
10.1530/jrf.0.1160293
复制
发表时间：
1999-07-01
期刊：
影响因子：
--
通讯作者：
Roche, JF
中科院分区：
文献类型：
--
作者：
Mihm, M;Curran, N;Roche, JF
本研究的目的是详细描述从占主导地位超过9天（排卵后生育力较低）的卵泡中恢复的牛卵母细胞的细胞质和核形态，并将形态变化与卵泡健康的卵泡内标记物联系起来。在发情周期的第二个优势卵泡（DF2）优势的第一天，肉牛接受前列腺素F-2 α和合成孕激素（3 mg Norgestomet） 2天或10天的治疗，在植入物移除后18小时，在预测的促性腺激素高峰之前，在卵巢切除术后的优势卵泡优势持续4天（n = 19; N2）或12天（n = 21; N10）。超声扫描确定5头N10小母牛在卵巢切除术前一天（n = 11）或当天（n = 4） （N10- nondom）出现新一波卵泡。剩余的N10小母牛（N10- dom）的优势卵泡在卵巢切除当天（17.8 +/- 0.6 mm）大于N2小母牛（13.6 +/- 0.4 mm） （P < 0.05）。N10-Dom母牛卵泡液雌二醇：黄体酮比值降低（21.7 +/- 3.1比34.1 +/- 4.4,P < 0.05），抑制素A（免疫放射测定）升高(12.7 +/- 1.0比9.0 +/- 0.7 μ g ml(-1)；P < 0.05)。12个N2卵母细胞中有11个表现出核激活，未发生生发囊泡破坏，而8个N10-Dom卵母细胞中有7个发生生发囊泡破坏，并进展到中期I（6/8）或II（1/8）。与N2卵母细胞相比，N10-Dom卵母细胞卵泡周围空间更大，卵浆中有更多的积云细胞过程终末，液泡、不规则囊泡，卵浆中有更多的线粒体和脂滴，但积云细胞的扩张和闭锁程度相似。因此，导致中期I的最终卵母细胞成熟是在大多数显性卵泡中开始的，在促性腺激素激增前的优势期为60 - 90天，并与显性卵泡健康的降低有关。然而，排卵能力被维持，并将导致老化的卵母细胞排卵，显着降低随后的怀孕率。
The aim of the present study was to characterize in detail the cytoplasmic and nuclear morphology of cattle oocytes recovered from follicles that are dominant for more than 9 days (with low fertility after ovulation), and to relate morphological changes to intrafollicular markers of follicle health. Beef heifers received prostaglandin F-2 alpha and a synthetic progestagen (3 mg Norgestomet) for 2 or 10 days on the first day of dominance of the second dominant follicle (DF2) of the oestrous cycle, to give a 4 day (n = 19; N2) or 12 day (n = 21; N10) duration of dominance of the dominant follicle at ovariectomy 18 h after implant removal and before the predicted gonadotrophin surge. Ultrasound scanning determined emergence of a new wave of follicles in five N10 heifers the day before (n = Ij or day of ovariectomy (n = 4) (N10-NonDom). Dominant follicles from the remaining N10 heifers (N10-Dom) were larger (P < 0.05) on the day of ovariectomy (17.8 +/- 0.6 mm) than those from N2 heifers (13.6 +/- 0.4 mm). The oestradiol:progesterone ratio of follicular fluid from N10-Dom heifers was reduced (21.7 +/- 3.1 versus 34.1 +/- 4.4; P < 0.05), while inhibin A las measured by immunoradiometric assay) was increased (12.7 +/- 1.0 versus 9.0 +/- 0.7 mu g ml(-1); P < 0.05) compared with N2 heifers. Eleven of twelve N2 oocytes demonstrated nuclear activation without germinal vesicle breakdown, while seven of eight N10-Dom oocytes had undergone germinal vesicle breakdown and had progressed to metaphase I (6/8) or II (1/8). Ln contrast to N2 oocytes, N10-Dom oocytes showed a larger perivitelline space containing more cumulus cell process endings, vacuoles, irregular vesicles, and more mitochrondia and lipid droplets throughout the ooplasm, yet the degree of cumulus cell expansion and atresia was similar. Thus, final oocyte maturation leading to metaphase I is initiated in most dominant follicles with a dominance period of > 9 days before the gonadotrophin surge and is associated with a reduction in dominant follicle health. However, ovulatory ability is maintained and will lead to the ovulation of aged oocytes, markedly reducing subsequent pregnancy rates.