Stevenson K R, Wathes D C
Department of Farm Animal and Equine Medicine and Surgery, Royal Veterinary College, Herts, UK.
J Reprod Fertil. 1996 Sep;108(1):31-40. doi: 10.1530/jrf.0.1080031.
The oviduct is the site of fertilization, and factors present in the oviductal fluid appear to be crucial to the future success of conceptus development. The spatial and temporal localization of mRNA encoding components of the insulin-like growth factor (IGF) system (IGF-I, IGF-II, the type 1 IGF receptor, and IGF-binding proteins -2, -3 and -4) in the ovine oviduct were examined in tissue samples taken during the early and late stages of follicular development, and the early, mid-, and late luteal phases using in situ hybridization. Expression of mRNA encoding IGF-I showed a cyclical pattern, increasing sharply in the mucosa and muscularis during the late follicular phase (P < or = 0.001), then declining. In the muscularis, mRNA encoding IGF-II exhibited no temporal changes, but concentrations in the mucosa increased from the late follicular stage to the early luteal phase. mRNA encoding the type 1 IGF receptor was present throughout the oviduct. Concentrations increased during the follicular phase to peak in the early luteal phase in both the mucosa and muscularis (P < 0.001). IGFBP-2 gene transcripts were undetectable at all time points examined. mRNAs encoding IGFBP-3 and IGFBP-4 were localized primarily in the stromal region. IGFBP-3 expression peaked in the late follicular stage of the cycle P < or = 0.001). The concentration of mRNA encoding IGFBP-4 increased in the follicular phase and was maintained at a significantly higher concentration during the early and mid-luteal stages (P < 0.001). The co-ordinate maximum expression of mRNA for both IGF-I and IGF-II, the type 1 IGF receptor and IGFBP-3 during the period when the gametes and embryo are in transit suggests a role for IGF-I and possibly IGF-II peptides in providing an oviductal environment propitious to conception and early embryonic growth and metabolism.
输卵管是受精的场所，输卵管液中的某些因素似乎对胚胎未来的成功发育至关重要。本研究采用原位杂交技术，检测了胰岛素样生长因子（IGF）系统各组分（IGF-I、IGF-II、1型IGF受体以及IGF结合蛋白-2、-3和-4）编码mRNA在绵羊输卵管中的时空定位，样本取自卵泡发育早期和晚期以及黄体形成的早、中、晚期。编码IGF-I的mRNA表达呈现周期性变化，在卵泡晚期，黏膜和肌层中的表达急剧增加（P≤0.001），随后下降。在肌层中，编码IGF-II的mRNA无时间变化，但黏膜中的浓度从卵泡晚期到黄体早期有所增加。编码1型IGF受体的mRNA在整个输卵管中均有表达。在卵泡期，黏膜和肌层中的浓度均增加，并在黄体早期达到峰值（P<0.001）。在所有检测时间点均未检测到IGFBP-2基因转录本。编码IGFBP-3和IGFBP-4的mRNA主要定位于基质区域。IGFBP-3的表达在周期的卵泡晚期达到峰值（P≤0.001）。编码IGFBP-4的mRNA浓度在卵泡期增加，并在黄体早期和中期维持在显著较高水平（P<0.001）。配子和胚胎在输卵管中移动期间，IGF-I、IGF-II、1型IGF受体以及IGFBP-3编码mRNA的协同最大表达，提示IGF-I以及可能的IGF-II肽在提供有利于受孕及早期胚胎生长和代谢的输卵管环境中发挥作用。
