Johnson A L
Center for Reproductive Biology and Health, and Department of Animal Science, The Pennsylvania State University, University Park 16802
Poult Sci. 2015 Apr;94(4):781-5. doi: 10.3382/ps/peu008. Epub 2014 Dec 22.
The reproductive strategy for avian species that produce a sequence (or clutch) of eggs is dependent upon the maintenance of a small cohort of viable, undifferentiated (prehierarchal) follicles. It is from this cohort that a single follicle is selected on an approximate daily basis to initiate rapid growth and final differentiation before ovulation. This review describes a working model in which follicles within this prehierarchal cohort are maintained in an undifferentiated state by inhibitory cell signaling until the time of selection. Ultimately, follicle selection represents a process in which a single undifferentiated follicle per day is predicted to escape such inhibitory mechanisms to begin rapid growth and final maturation before ovulation. Several processes initiated within the granulosa cell layer at selection are dependent upon G protein-coupled receptors signaling via cyclic adenosine monophosphate (cAMP), and several critical processes are described herein. Finally, reference is made to several practical outcomes that can result from understanding the process of selection, including applications within the poultry industry. Proximal factors and processes that mediate follicle selection can either extend or decrease the length of the laying sequence, and thus directly influence overall egg production. In particular, any aberration that results in the selection of more than one follicle per day will result in decreased egg production. More generally, in wild birds these processes are modified by prevailing environmental conditions and by social interactions to influence clutch size. The elucidation of cellular processes that regulate follicle selection can assist in the development of assisted reproductive technologies for application in threatened and endangered avian species.
对于产蛋有先后顺序（或一窝蛋）的鸟类物种而言，其繁殖策略依赖于一小群存活的、未分化（等级前）卵泡的维持。正是从这群卵泡中，每天大约挑选出一个卵泡，使其在排卵前开始快速生长并最终分化。本综述描述了一个工作模型，在该模型中，等级前卵泡群中的卵泡通过抑制性细胞信号维持在未分化状态，直至被挑选之时。最终，卵泡选择代表了这样一个过程，预计每天有一个未分化卵泡逃脱这种抑制机制，从而在排卵前开始快速生长并最终成熟。在挑选时颗粒细胞层内启动的几个过程依赖于通过环磷酸腺苷（cAMP）进行信号传导的G蛋白偶联受体，本文描述了几个关键过程。最后，提及了理解卵泡选择过程可能产生的几个实际成果，包括在禽业中的应用。介导卵泡选择的近端因素和过程可以延长或缩短产蛋序列的长度，从而直接影响总体产蛋量。特别是，任何导致每天挑选一个以上卵泡的异常情况都会导致产蛋量下降。更一般地说，在野生鸟类中，这些过程会受到当前环境条件和社会互动的影响，以影响窝卵数。阐明调节卵泡选择的细胞过程有助于开发辅助生殖技术，用于濒危鸟类物种。
