Christenson R K, Ford J J, Redmer D A
J Reprod Fertil Suppl. 1985;33:21-36.
The processes of follicle development and puberty are closely related, and both are associated with maturation of the hypothalamic-pituitary-ovarian axis. Prenatal development of the ovary is independent of gonadotrophic stimulation. Beyond 60 days of age (postnatally), tertiary follicles develop and gonadotrophins begin to influence ovarian follicular development. Negative feedback regulation of pituitary gonadotrophins by ovarian secretions develops between 60 and 100 days of age. In the prepubertal gilt, no consistent changes in peripheral FSH, oestrogen or progesterone concentrations have been identified which are associated with recruitment of the first set of preovulatory follicles. Whether LH secretion increases before this recruitment remains equivocal. Few details are available on how gonadotrophic hormones stimulate ovarian function in the prepubertal gilt. On the basis of a follicular maturation model that has been described for the rat, the actions of FSH, LH and oestrogens on follicular cell receptors and the regulation of aromatase activity seem paramount. Aromatization of androgens to oestrogens has been proposed as a central regulator for follicular maturation. In the prepubertal gilt, a selective increase in peripheral FSH concentration occurs on Day 1 after unilateral ovariectomy, followed by significant increases in ovarian venous concentrations of oestradiol and inhibin on Days 2 and 4 and compensatory growth as measured by follicular fluid volume on Days 2, 4 and 8. Administration of pig follicular fluid to the prepubertal gilt during and after unilateral ovariectomy suppresses compensatory ovarian hypertrophy by mechanisms yet to be determined. In pigs a number of intraovarian factors have been identified, but there is little information on how these factors regulate follicular recruitment and growth. The factor(s) that prevents ovarian follicles in the prepubertal gilt from progressing to ovulation after acquiring the ability to ovulate in response to exogenous gonadotrophins remains unknown.
卵泡发育过程与青春期密切相关，二者均与下丘脑 - 垂体 - 卵巢轴的成熟有关。卵巢的产前发育独立于促性腺激素刺激。出生后60天以后，三级卵泡开始发育，促性腺激素开始影响卵巢卵泡发育。卵巢分泌对垂体促性腺激素的负反馈调节在60至100日龄之间形成。在青春期前的小母猪中，尚未发现外周促卵泡激素（FSH）、雌激素或孕酮浓度有与第一批排卵前卵泡募集相关的一致变化。促黄体生成素（LH）分泌在这种募集之前是否增加仍不明确。关于促性腺激素如何刺激青春期前小母猪的卵巢功能，目前所知甚少。基于已描述的大鼠卵泡成熟模型，FSH、LH和雌激素对卵泡细胞受体的作用以及芳香化酶活性的调节似乎至关重要。雄激素向雌激素的芳香化作用被认为是卵泡成熟的核心调节因素。在青春期前的小母猪中，单侧卵巢切除术后第1天外周FSH浓度选择性增加，随后在第2天和第4天卵巢静脉中雌二醇和抑制素浓度显著增加，并且在第2天、第4天和第8天通过卵泡液体积测量显示有代偿性生长。在单侧卵巢切除术中及术后给青春期前小母猪注射猪卵泡液，可通过尚未确定的机制抑制代偿性卵巢肥大。在猪中已鉴定出多种卵巢内因子，但关于这些因子如何调节卵泡募集和生长的信息很少。在青春期前的小母猪中，获得对外源促性腺激素排卵能力后，阻止卵巢卵泡排卵的因素仍然未知。
