Etches R J, Petitte J N
Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
J Exp Zool Suppl. 1990;4:112-22. doi: 10.1002/jez.1402560419.
The presence of an ovarian follicular hierarchy is a characteristic feature of reptiles and birds. The hierarchy contains follicles at all stages of maturation and therefore, varying degrees of sensitivity to the ovulation-inducing effects of the gonadotropins. In the hen, ovulability is gained as the ability of the follicle to produce androgens and estrogens declines and the ability to produce progesterone increases. In the mature follicle, the granulosa cells are the site of progesterone production whereas the theca cells produce androgens and estrogens. Small follicles that have not yet been (and may never be) recruited into the yolk-filled hierarchy are the major producers of androgens and estrogens within the ovary. In reptiles the ovarian follicular hierarchy includes non-vitellogenic follicles and in some species includes follicles destined to become atretic. These two features distinguish the reptiles from the birds and provide experimental biologists with a unique model to investigate the physiological events that regulate the most common fate of ovarian follicles, atresia.
卵巢卵泡分级系统的存在是爬行动物和鸟类的一个特征。该分级系统包含处于所有成熟阶段的卵泡，因此，对促性腺激素诱导排卵的作用具有不同程度的敏感性。在母鸡中，随着卵泡产生雄激素和雌激素的能力下降以及产生孕酮的能力增加，卵泡获得了排卵能力。在成熟卵泡中，颗粒细胞是孕酮产生的部位，而卵泡膜细胞产生雄激素和雌激素。尚未（且可能永远不会）被纳入充满卵黄的分级系统的小卵泡是卵巢内雄激素和雌激素的主要产生者。在爬行动物中，卵巢卵泡分级系统包括非卵黄生成卵泡，在某些物种中还包括注定会闭锁的卵泡。这两个特征将爬行动物与鸟类区分开来，并为实验生物学家提供了一个独特的模型，用于研究调节卵巢卵泡最常见命运——闭锁的生理事件。
