Atkinson S, Williamson P
J Reprod Fertil. 1985 Jan;73(1):185-9. doi: 10.1530/jrf.0.0730185.
Southdown ewes in mid-seasonal anoestrus were exposed to rams for 0 h (control group), 2 h, 24 h, 40 h, 3 days, 10 days or 20 days. Serial blood samples were then taken to determine LH and FSH levels. Ewes with greater than 24 h ram exposure were ovariectomized immediately after bleeding, and all follicles greater than 1 mm diameter were dissected from the ovaries and measured. LH basal concentrations and pulse frequency increased significantly within 2 h of ram introduction, but by 24 h fell, and then remained low. FSH concentrations fell within 2 h of ram introduction and remained low. Control group ewes (isolated) had no follicles greater than 4 mm diameter, whereas all ewes exposed to rams had large follicles, with CL or preovulatory follicles present at 40 h after ram introduction. Ram introduction was also associated with follicle recruitment (antrum formation to less than 2 mm). Follicular recruitment and development to the large follicle stage therefore occurred during a period of low plasma gonadotrophin levels and suppressed LH pulsing.
处于季节性发情中期的萨福克母羊与公羊接触0小时（对照组）、2小时、24小时、40小时、3天、10天或20天。然后采集系列血样以测定促黄体生成素（LH）和促卵泡素（FSH）水平。接触公羊超过24小时的母羊在采血后立即进行卵巢切除，从卵巢中解剖出所有直径大于1毫米的卵泡并进行测量。引入公羊后2小时内，LH基础浓度和脉冲频率显著增加，但到24小时时下降，然后保持在低水平。引入公羊后2小时内FSH浓度下降并保持在低水平。对照组母羊（隔离状态）没有直径大于4毫米的卵泡，而所有接触公羊的母羊都有大卵泡，引入公羊后40小时出现黄体或排卵前卵泡。引入公羊还与卵泡募集（腔形成至小于2毫米）有关。因此，卵泡募集和发育至大卵泡阶段发生在血浆促性腺激素水平较低且LH脉冲受到抑制的时期。
