University of Missouri, Division of Animal Sciences, 920 E. Campus Drive, Columbia, MO 65211, USA.
Anim Reprod Sci. 2010 Jan;117(1-2):43-54. doi: 10.1016/j.anireprosci.2009.02.010. Epub 2009 Feb 21.
To better understand the role of estradiol-17beta in fetal ovarian development, presence and localization of cytochrome P450 aromatase (P450arom) and estrogen receptors alpha (ERalpha) and beta (ERbeta) proteins were characterized in fetal ovaries of cattle using immunohistochemistry. Fetal cattle ovaries were collected from an abattoir and sorted into fetal age groups (days 110, 130, 150, 170, 190, 210, 230, 250+) based on crown-rump length. In addition to immunohistochemistry, morphological analysis of ovarian and follicular formation was made. Ovaries appeared lobular at day 110, but by the end of gestation (day 250+) ovaries were oval-shaped similar to those found in adult animals. Ovarian structures within different lobes appeared to be at different developmental stages. At day 110, oocytes and pre-granulosa cells were observed in ovigerous cords that were still open to the surface epithelium. Most ovigerous cords appeared to be closed to the surface epithelium on day 130, all closed by day 150 and were no longer present at day 210. Ovarian follicles were classified as follows: Type 1(primordial): single layer of flattened granulosa cells, Type 1a (transitory): single layer of mixed flattened and cuboidal granulosa cells, Type 2 (primary): at least one but less than two layers of cuboidal granulosa cells, Type 3 (small preantral): two to three layers of granulosa cells, Type 4 (large preantral): four to six layers of granulosa, and the theca layer is forming around the follicle, Type 5 (antral): contain greater than six layers of granulosa cells, several layers of theca cells and the antrum has formed. Type 1 follicles were observed in day 110 ovaries. Follicle Types 1a and 2 were first observed on day 130. Type 3 follicles were first observed on day 150 and Types 4 and 5 were first observed on day 170. P450arom protein was localized in granulosa cells of follicle Types 2-5 and cells of rete tubules throughout the experimental period. There was punctate expression within stroma and rete masses. There was ERalpha protein localization in pre-granulosa cells and germ cells of ovigerous cords and all surface epithelial cells. There was also localization in granulosa cells and oocytes of all follicle types and cells of rete tubules. There was punctate ERalpha protein expression in stroma and rete masses. ERbeta protein was localized in pre-granulosa cells and germ cells of ovigerous cords. Expression was also localized to granulosa cells of all follicle types and cells of rete tubules. ERbeta protein was punctate in oocytes of follicles, surface epithelial cells, stroma and rete masses. Thus, the fetal ovary of cattle has the steroidogenic enzyme (P450arom) to convert androgens to estradiol-17beta, and estrogen receptors alpha and beta to facilitate an estrogen response within the fetal ovary.
为了更好地了解雌二醇-17β在胎儿卵巢发育中的作用，我们使用免疫组织化学的方法研究了牛胎儿卵巢中细胞色素 P450 芳香化酶（P450arom）和雌激素受体 α（ERα）和 β（ERβ）蛋白的存在和定位。从屠宰场收集牛胎儿卵巢，并根据头臀长将其分为胎儿年龄组（第 110、130、150、170、190、210、230、250+ 天）。除免疫组织化学外，还对卵巢和卵泡形成的形态进行了分析。第 110 天，卵巢呈小叶状，但在妊娠末期（第 250+ 天），卵巢呈椭圆形，与成年动物的卵巢相似。不同小叶内的卵巢结构似乎处于不同的发育阶段。第 110 天，卵母细胞和原始卵泡细胞存在于卵黄原纤维中，卵黄原纤维仍与表面上皮相通。第 130 天，大多数卵黄原纤维似乎与表面上皮相通，第 150 天完全相通，第 210 天不再存在。卵巢卵泡分为以下几类：1 型（原始）：单层扁平颗粒细胞；1a 型（过渡）：单层混合扁平细胞和立方状颗粒细胞；2 型（初级）：至少有一层，但不到两层的立方状颗粒细胞；3 型（小前腔）：两层至三层颗粒细胞；4 型（大前腔）：四至六层颗粒细胞，并且卵泡周围有膜层；5 型（腔）：包含超过六层的颗粒细胞，几层膜细胞和腔已形成。第 110 天的卵巢中观察到 1 型卵泡。第 130 天首次观察到 1a 型和 2 型卵泡。第 150 天首次观察到 3 型卵泡，第 170 天首次观察到 4 型和 5 型卵泡。P450arom 蛋白定位于卵泡 2-5 型的颗粒细胞和整个实验期间的 rete 小管细胞中。基质和 rete 团块中有点状表达。在卵黄原纤维和所有表面上皮细胞中，存在 ERα 蛋白在原始颗粒细胞和生殖细胞中的定位。在所有卵泡类型的颗粒细胞和卵母细胞以及 rete 小管细胞中也有定位。基质和 rete 团块中有 ERα 蛋白的点状表达。ERβ 蛋白定位于卵黄原纤维和生殖细胞中的原始颗粒细胞。在所有卵泡类型的颗粒细胞和 rete 小管细胞中也有表达。在卵泡的卵母细胞、表面上皮细胞、基质和 rete 团块中，ERβ 蛋白呈点状。因此，牛胎儿卵巢具有将雄激素转化为雌二醇-17β的甾体生成酶（P450arom），以及雌激素受体 α 和 β，以促进胎儿卵巢内的雌激素反应。
