Fair T, Hyttel P, Greve T, Boland M
Department of Anatomy and Physiology, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
Mol Reprod Dev. 1996 Apr;43(4):503-12. doi: 10.1002/(SICI)1098-2795(199604)43:4<503::AID-MRD13>3.0.CO;2-#.
Bovine abattoir ovaries were sliced, and recovered oocytes were washed and incubated in medium enriched with 3H-uridine for 30 min. Uridine incorporation was stopped by washing at 4 degrees C in PBS supplemented with cold uridine. The oocytes were grouped according to their inside diameter- < 100, 100- < 110, 110- < 120, and > or = 120 microns-and processed for autoradiography and transmission electron microscopy. Oocytes < 110 microns in diameter typically presented fibrillogranular nucleoli and were actively transcribing; in contrast, most oocytes > 110 microns displayed electron-dense fibrillar nucleoli and lacked transcriptional activity, as measured by the present means. Based on morphological and transcriptional information, a dynamic model of nucleolus inactivation is proposed. The degree of chromatin condensation varied among oocytes. Fibrillogranular nucleoli were most frequently accompanied by lightly condensed chromatin. The dense fibrillar nucleoli were usually encapsulated by heavily condensed chromatin. The oocyte nuclei underwent a peripheral translocation as the oocyte diameter increased from < 100 to 110 microns. In conclusion, RNA synthesis appeared to cease as the oocyte diameter exceeded 110 microns, and concomitantly the nucleoli restructured from fibrillogranular to dense fibrillar.
将牛屠宰场的卵巢切片，回收的卵母细胞经清洗后，置于富含3H - 尿苷的培养基中孵育30分钟。通过在补充有冷尿苷的PBS中于4℃洗涤来终止尿苷掺入。根据卵母细胞的内径将其分组——<100、100 - <110、110 - <120以及≥120微米——并进行放射自显影和透射电子显微镜检查处理。直径<110微米的卵母细胞通常呈现纤维颗粒状核仁且正在进行活跃转录；相比之下，通过本方法测量，大多数直径>110微米的卵母细胞显示电子致密的纤维状核仁且缺乏转录活性。基于形态学和转录信息，提出了核仁失活的动态模型。卵母细胞中染色质凝聚程度各不相同。纤维颗粒状核仁最常伴随着轻度凝聚的染色质。致密纤维状核仁通常被高度凝聚的染色质包裹。随着卵母细胞直径从<100微米增加到110微米，卵母细胞核发生外周移位。总之，当卵母细胞直径超过110微米时，RNA合成似乎停止，同时核仁从纤维颗粒状重构为致密纤维状。
