Dubois P M
CNRS-URA 559, Université Claude Bernard-Lyon I, Faculté de Médecine Lyon-Sud, Oullins.
Ann Endocrinol (Paris). 1990;51(2):47-53.
In human fetus, gonadotrophs were first detected at eight weeks of gestation. In fact, at this stage of gestation, the gonadotrophs essentially synthesize the alpha subunit of glycoprotein hormones. It is noteworthy that alpha synthesis exist during all the gestation. The profile of the secretion of LH and FSH is different according to the age and sex. It is likely that the regulation of gonadotrophs is depending on gonadoliberin (GnRH). It has been detected precociously in fetal brain, and both in vivo and in vitro studies have provided fairly convincing evidence for gonadotroph responsiveness to GnRH. The analysis of factors controlling the hypophysial differentiation was made in Rat. Gonadotrophs were first detected at 17 days of gestation in normal rat fetus. Since encephalectomy performed at 16 days of gestation did not modify the gonadotroph aspect, the organ culture method was developed to analyze these factors. In adenohypophysial primordia explanted at 11 and 12 days of gestation, GnRH 10(-9) to 10(2) M was required for the first 24 hours of culture to induce gonadotroph differentiation which was obtained in synergy with insulin and transferrin. On the other hand fetal hypothalamic GnRH and pituitary GnRH receptors were observed from 12 days of gestation. Although GnRH can be demonstrated in human fetal hypothalamus as early as 5-8 weeks of gestation, it is difficult to assess what role this peptide may have in differentiation of gonadotrophs.
在人类胎儿中，促性腺激素细胞在妊娠8周时首次被检测到。事实上，在妊娠的这个阶段，促性腺激素细胞主要合成糖蛋白激素的α亚基。值得注意的是，α亚基的合成在整个妊娠期都存在。促黄体生成素（LH）和促卵泡生成素（FSH）的分泌情况因年龄和性别而异。促性腺激素细胞的调节可能依赖于促性腺激素释放激素（GnRH）。它在胎儿脑中被过早检测到，体内和体外研究都为促性腺激素细胞对GnRH的反应性提供了相当有说服力的证据。对大鼠垂体前叶分化控制因素进行了分析。在正常大鼠胎儿中，促性腺激素细胞在妊娠17天时首次被检测到。由于在妊娠16天时进行脑切除并未改变促性腺激素细胞的形态，因此开发了器官培养方法来分析这些因素。在妊娠11天和12天取出的腺垂体原基中，培养的前24小时需要10(-9)至10(2)M的GnRH来诱导促性腺激素细胞分化，这与胰岛素和转铁蛋白协同作用可实现。另一方面，从妊娠12天开始观察到胎儿下丘脑GnRH和垂体GnRH受体。尽管早在妊娠5至8周时就可在人类胎儿下丘脑中证实GnRH的存在，但很难评估这种肽在促性腺激素细胞分化中可能起什么作用。
