Noseir Wael M B
Department of Theriogenology, Faculty of Veterinary Medicine, Alexandria University, Egypt.
Reprod Biol Endocrinol. 2003 Jun 21;1:50. doi: 10.1186/1477-7827-1-50.
Most estrous cycles in cows consist of 2 or 3 waves of follicular activity. Waves of ovarian follicular development comprise the growth of dominant follicles some of which become ovulatory and the others are anovulatory. Ovarian follicular activity in cows during estrous cycle was studied with a special reference to follicular waves and the circulating concentrations of estradiol and progesterone. Transrectal ultrasound examination was carried out during 14 interovulatory intervals in 7 cows. Ovarian follicular activity was recorded together with assessment of serum estradiol and progesterone concentrations. Three-wave versus two-wave interovulatory intervals was observed in 71.4% of cows. The 3-wave interovulatory intervals differed from 2-wave intervals in: 1) earlier emergence of the dominant follicles, 2) longer in length, and 3) shorter interval from emergence to ovulation. There was a progressive increase in follicular size and estradiol production during growth phase of each wave. A drop in estradiol concentration was observed during the static phase of dominant anovulatory follicles. The size of the ovulatory follicle was always greater and produced higher estradiol compared with the anovulatory follicle. In conclusion, there was a predominance of 3-wave follicular activity that was associated with an increase in length of interovulatory intervals. A dominant anovulatory follicle during its static phase may initiate the emergence of a subsequent wave. Follicular size and estradiol concentration may have an important role in controlling follicular development and in determining whether an estrous cycle will have 2 or 3-waves.
大多数奶牛的发情周期由2或3个卵泡活动波组成。卵巢卵泡发育波包括优势卵泡的生长，其中一些优势卵泡会排卵，而其他的则不排卵。本研究特别参考卵泡波以及雌二醇和孕酮的循环浓度，对奶牛发情周期中的卵巢卵泡活动进行了研究。对7头奶牛的14个排卵间期进行了经直肠超声检查。记录卵巢卵泡活动情况，并评估血清雌二醇和孕酮浓度。71.4%的奶牛观察到三波与两波排卵间期。三波排卵间期与两波排卵间期的不同之处在于：1）优势卵泡更早出现，2）长度更长，3）从出现到排卵的间隔更短。在每一波的生长阶段，卵泡大小和雌二醇产量都有逐渐增加。在优势无排卵卵泡的静止期观察到雌二醇浓度下降。与无排卵卵泡相比，排卵卵泡的大小总是更大，产生的雌二醇更高。总之，三波卵泡活动占主导，这与排卵间期长度增加有关。优势无排卵卵泡在其静止期可能会引发后续波的出现。卵泡大小和雌二醇浓度可能在控制卵泡发育以及确定发情周期是两波还是三波方面发挥重要作用。
