Animal Science, School of Agricultural Sciences, Southern Illinois University, Carbondale, Illinois, USA.
Department of Veterinary Medicine, Sousa Campus, Federal Institute of Education, Science and Technology of Paraíba, Sousa, Paraíba, Brazil.
Reprod Fertil. 2022 Apr 4;3(2):90-102. doi: 10.1530/RAF-21-0100. eCollection 2022 Apr 1.
Characterization of the ovarian preantral follicle population is a necessary step to improve understanding of folliculogenesis and ovarian physiology. Therefore, in the present study, the preantral follicle population in the equine ovary in young and old mares was investigated according to follicular morphology, follicular class, distance from the geometric center using ovarian maps, and follicular density within ovarian portions (lateral vs intermediary) and regions (dorsal vs ventral). Ovaries were collected from an abattoir and histologically processed for evaluation, and the follicle population was calculated. Overall, in the current detailed study, a higher preantral follicle population per mare ovary (mean: 82,206 ± 50,022; range: 1477 to 773,091) than originally reported was identified. Additionally, a mare age effect was observed in the follicle population (young: 152,664 vs old: 11,750) and the spatial distribution of morphologically normal and abnormal follicles and the density and population of follicular classes. These results demonstrate that, in addition to the preantral follicle population in the mare ovary being comparable to that of other species, the location and spatial distribution of these follicles is dynamic and varies depending on mare age and follicle status (i.e. morphology and developmental stage). The characterization of the distribution and population of preantral follicles in the mare ovary provided by this study can potentially aid in improving reproductive studies and assisted reproductive techniques and may expand the understanding of mechanisms involving ovarian plasticity and follicular migration.
Knowledge of the distribution and population of immature eggs within follicles (preantral follicles) in the ovaries of mares can improve approaches to assisted reproductive techniques and fertility preservation. As the existing research on horse preantral follicle population was focused solely on large follicles, the present study provides an updated investigation of small and large preantral follicles in the mare, showing that the population is similar to those in other species. This study also shows that the way these follicles are distributed in the ovary varies depending on age and follicle characteristics. Results from this study may help to highlight which areas of the mare ovary should be looked at to find samples of good-quality follicles.
对卵巢原始卵泡群体进行特征分析是提高对卵泡发生和卵巢生理学理解的必要步骤。因此，在本研究中，根据卵泡形态、卵泡类别、使用卵巢图谱的几何中心距离以及卵巢部分（外侧与中间）和区域（背侧与腹侧）内的卵泡密度，研究了年轻和老年母马的卵巢原始卵泡群体。从屠宰场采集卵巢并进行组织学处理以进行评估，并计算卵泡群体。总体而言，在当前详细的研究中，每只母马卵巢的原始卵泡数量（平均值：82206 ± 50022；范围：1477 至 773091）比之前报道的要高。此外，还观察到母马年龄对卵泡数量（年轻：152664 与老年：11750）以及形态正常和异常卵泡的空间分布以及卵泡类别密度和数量有影响。这些结果表明，除了母马卵巢中的原始卵泡数量与其他物种相当之外，这些卵泡的位置和空间分布是动态的，并且取决于母马年龄和卵泡状态（即形态和发育阶段）而变化。本研究对母马卵巢中原始卵泡的分布和数量的特征分析有助于改善生殖研究和辅助生殖技术，并可能扩大对涉及卵巢可塑性和卵泡迁移的机制的理解。
了解马卵巢卵泡（原始卵泡）内未成熟卵的分布和数量可以改进辅助生殖技术和生育力保存方法。由于现有关于马原始卵泡群体的研究仅集中在大卵泡上，因此本研究对马的小卵泡和大卵泡进行了更新的调查，结果表明其群体与其他物种相似。本研究还表明，这些卵泡在卵巢中的分布方式取决于年龄和卵泡特征。本研究的结果可能有助于突出应该在马卵巢的哪些区域寻找高质量卵泡样本。
