Yao H H, Volentine K K, Bahr J M
Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Biol Reprod. 1998 Sep;59(3):516-21. doi: 10.1095/biolreprod59.3.516.
The germinal disc region (GDR), which contains the germinal disc and overlying granulosa cells, is essential for completion of maturation of the preovulatory chicken follicle. The current study was conducted to test the hypothesis that destruction of the GDR (GDRX) of an immature preovulatory chicken follicle blocks ovulation, induces apoptosis, and causes atresia. The GDR of immature preovulatory follicles (F2) were destroyed by freezing with dry ice (3 mm in diameter) 48-50 h before ovulation. As a control for the effect of freezing, a nonGDR portion (a portion of the follicular wall opposite to the GDR relative to the follicular stalk) of other F2 follicles were destroyed (nonGDRX). Treatment of F2 follicles by GDRX caused atresia and blocked ovulation of all treated follicles (6 of 6), whereas none of the nonGDRX follicles (0 of 5) underwent atresia. Treatment of follicles by GDRX induced apoptotic DNA fragmentation (laddering) in theca and granulosa layers obtained from the frozen area and in the theca layer obtained from the follicular wall distal to the frozen area. In contrast, apoptosis was only present in theca and granulosa layers in the frozen area of the nonGDRX follicle. Furthermore, the in situ DNA end-labeling technique demonstrated that in the GDRX follicle 24 h after treatment, cells in the theca interna, endothelial cells in blood vessels of the theca externa, and a few granulosa cells underwent apoptosis. These results indicate that destruction of the GDR of an immature preovulatory follicle causes atresia and apoptosis and blocks ovulation. These novel findings suggest that the GDR maintains development of the chicken preovulatory follicle by producing one or more survival factors. Without the GDR, chicken follicles cannot develop further and they eventually die.
胚盘区（GDR）包含胚盘和覆盖其上的颗粒细胞，对于排卵前鸡卵泡成熟的完成至关重要。本研究旨在验证以下假设：破坏未成熟排卵前鸡卵泡的胚盘区（GDRX）会阻止排卵、诱导细胞凋亡并导致卵泡闭锁。在排卵前48 - 50小时，用干冰（直径3毫米）冷冻破坏未成熟排卵前卵泡（F2）的胚盘区。作为冷冻效果的对照，破坏其他F2卵泡的非胚盘区部分（相对于卵泡柄，与胚盘区相对的卵泡壁部分）（非GDRX）。GDRX处理F2卵泡导致卵泡闭锁，并阻止了所有处理卵泡的排卵（6个中的6个），而没有一个非GDRX卵泡（5个中的0个）发生闭锁。GDRX处理卵泡诱导了从冷冻区域获得的卵泡膜和颗粒层以及从冷冻区域远端的卵泡壁获得的卵泡膜层中的凋亡性DNA片段化（梯状条带）。相比之下，凋亡仅存在于非GDRX卵泡冷冻区域的卵泡膜和颗粒层中。此外，原位DNA末端标记技术表明，在处理后24小时的GDRX卵泡中，卵泡内膜细胞、卵泡外膜血管内皮细胞和少数颗粒细胞发生了凋亡。这些结果表明，破坏未成熟排卵前卵泡的胚盘区会导致卵泡闭锁和细胞凋亡，并阻止排卵。这些新发现表明，胚盘区通过产生一种或多种存活因子维持鸡排卵前卵泡的发育。没有胚盘区，鸡卵泡无法进一步发育，最终死亡。
