Hirshfield A N
Department of Anatomy, University of Maryland School of Medicine, Baltimore 21201.
Biol Reprod. 1989 Aug;41(2):309-16. doi: 10.1095/biolreprod41.2.309.
It is generally believed that in adult rodents the vast majority of very small follicles (less than 20 granulosa cells in cross section) are not growing. However, the only data to support this assumption were collected with methods that may not be sufficiently sensitive to distinguish between nongrowing follicles and slowly growing follicles. In this study, the method of long-term continuous [3H]thymidine (3H-TdR) infusion was used to examine growth of very small follicles. Young adult rats were given continuous infusions of 3H-TdR for up to 7 days. Autoradiographs were prepared from 2-microns-thick sections of the ovaries. The proportion of labeled very small follicles increased as the duration of the infusion increased. After 7 days of continuous 3H-TdR infusion, 37% of follicles with 4 or fewer granulosa cells had at least one labeled granulosa cell, as did 68% of follicles with 5 8 granulosa cells, 86% of follicles with 9 12 granulosa cells, and 100% of follicles with 13 or more granulosa cells. The number of labeled cells per labeled follicle (the labeling index) also increased with increasing infusion time. However, few follicles had labeling indices of 100%, even after 7 days of continuous 3H-TdR infusion. These results suggest that a substantial fraction of very small follicles is growing in adult cycling rats; however, the rate of growth appears to be quite slow.
一般认为，在成年啮齿动物中，绝大多数非常小的卵泡（横截面积小于20个颗粒细胞）并未生长。然而，支持这一假设的唯一数据是通过可能不够灵敏以区分非生长卵泡和缓慢生长卵泡的方法收集的。在本研究中，采用长期连续输注[3H]胸腺嘧啶核苷（3H-TdR）的方法来检测非常小的卵泡的生长情况。给年轻成年大鼠连续输注3H-TdR长达7天。从卵巢的2微米厚切片制备放射自显影片。随着输注持续时间的增加，标记的非常小的卵泡的比例增加。连续输注3H-TdR 7天后，4个或更少颗粒细胞的卵泡中有37%至少有一个标记的颗粒细胞，5至8个颗粒细胞的卵泡中有68%，9至12个颗粒细胞的卵泡中有86%，13个或更多颗粒细胞的卵泡中有100%。每个标记卵泡中的标记细胞数量（标记指数）也随着输注时间的增加而增加。然而，即使连续输注3H-TdR 7天，很少有卵泡的标记指数达到100%。这些结果表明，成年周期性大鼠中相当一部分非常小的卵泡正在生长；然而，生长速度似乎相当缓慢。
