大鼠卵泡细胞的程序发育和类胰岛素生长因子Ⅱ的表达

THE PROGRAMMED SEQUENCE DEVELOPMENT OF THE FOLLICULAR CELLS OF RAT AND INSULIN-LIKE GROWTH FACTOR-Ⅱ GENE EXPRESSION

用孕马血清（ＰＭＳＧ）、人绒毛膜促性腺激素（ｈＣＧ）刺激２０ｄ雌性大鼠。然后在ｈＣＧ刺激的不同时程处死动物，用细胞生物学方法和分子生物学原位杂交方法，观察卵泡细胞形态学的改变，以及卵泡内的类胰岛素生长因子－Ⅱ（ＩＧＦ－Ⅱ）在该动物卵泡细胞的动态表达。在ＰＭＳＧ刺激４８ｈ后，卵泡开始发育成对促性腺激素有应答反应或对其依赖的卵泡、内泡膜细胞和颗粒细胞增殖，甘油三脂滴（ＴＧＤ）大量堆积在内泡膜细胞的胞浆中，外泡膜细胞不含ＴＧＤ，同时ＩＧＦ－Ⅱ基因开始在颗粒细胞核中复制和转录。ＰＭＳＧ刺激４８ｈ后，ｈＣＧ又刺激１２ｈ，内泡膜细胞和颗粒细胞胞浆中的ＴＧＤ消失，血管内皮细胞向颗粒细胞腔迁移，颗粒黄体细胞开始形成，未排卵卵泡的内泡膜细胞发育成分泌腺样结构，大量ＴＧＤ堆积在胞浆中。ｈＣＧ刺激２４ｈ后，ＩＧＦ－ＩＩ基因的转录和表达达到最高水中，在颗粒细胞的胞浆中出现杂交信号。本实验证明，未成年大鼠在程序化的外源性促性腺激素控制下，有应答反应的一组卵泡细胞，经卵泡内的因子ＩＧＦ－ＩＩ协调可进入程序化的发育过程：特别是卵泡的内泡膜细胞中的甾体类合成前体物甘油三脂滴可以有规律地堆积和释放。

A hypothesis was proposed that there is a programmed sequence of follicular cell development in a group of gonadotrophin-response follicles. The 20-day-female rats were stimulated by pregnant mare's serum gonadotrophin(PMSG) and human chorionic gonadotrophin(hCG) subsequently and were killed in several different intervals of hCG stimulation. The cell biological method and the in situ hybridization of ovarian tissues with IGF-Ⅱ cDNA probe were carried out. After 48h of PMSG stimulation, the follicles began to develop the gonadotrophin-response or gonadotrophin-dependent follicles,the theca interna and granulosa cells to proliferate,triglyceride droplets(TGD) were larger amount in the theca interna cells than in the granulosa cells, no TGD in the theca externa cells. At the same time IGF-Ⅱ gene began to be transcribed and replicated in the nuclei of the granulosa cells. After PMSG stimulation of 48h followed by 12h hCG stimulation, the TGD disappeared from some theca interna cells and granulosa cells ,endothelial cells migrated into the compartment of the granulosa cells and luteum-granulosa cells began formation. There was large amount of TGD in the theca interna cell's cytoplasm of the non-ovulating follicles, IGF-Ⅱgene was transcribed and expressed to high level in the granulosa cells until 24h hCG stimulation. These results proved an evidence to demonstrate the hypothesis of the programmed sequence development in a group of follicles of immature rats controlled by the programmed sequence of exogenous hormone signals, which coordinated by intra-ovarian factor IGF-Ⅱ.