Böckers T M, Bockmann J, Fauteck J D, Kreutz M R, Bock R, Wittkowski W
Institute of Anatomy, University of Münster, Germany.
Eur J Endocrinol. 1994 Nov;131(5):540-6. doi: 10.1530/eje.0.1310540.
The ovine pituitary pars tuberalis was investigated by electron microscopy, immunocytochemistry and non-radioactive in situ hybridization in order to characterize further the pars tuberalis-specific cells, whose functional role within the endocrine system is still enigmatic. Ultrastructural analysis revealed that, besides gonadotropic cells, the vast majority of cells in the ovine pars tuberalis show the typical characteristics of pars tuberalis-specific cells with clear signs of secretory activity. Immunocytochemical staining with a polyclonal antibody directed against the alpha-subunit of ovine glycoprotein hormones and in situ hybridization with an antisense oligonucleotide complementary to the alpha-subunit mRNA showed that the common alpha-chain of glycoprotein hormones is expressed in pars tuberalis-specific cells. Antibodies against the beta-subunits failed to detect any of the known beta-chains of pituitary glycoprotein hormones in these cells. The demonstration of the glycoprotein alpha-subunit in pars tuberalis-specific cells of the adult sheep supports previously existing evidence that these cells do secrete one or more glycoprotein hormones. With respect to the thyrotropin-beta-like immunoreactivity in rats and hamsters, one might speculate that pars tuberalis-specific cells are a pluripotent cell type with a low secretory activity under basal conditions. Further studies should prove the hypothesis that a pre-existing mRNA pool in these cells can be used for sustained translation of glycoprotein hormones after physiological or pharmacological stimulation.
为了进一步明确结节部特异性细胞的特征，对绵羊垂体结节部进行了电子显微镜、免疫细胞化学和非放射性原位杂交研究，这些细胞在内分泌系统中的功能作用仍不清楚。超微结构分析显示，除促性腺细胞外，绵羊结节部的绝大多数细胞呈现出结节部特异性细胞的典型特征，并具有明显的分泌活性迹象。用针对绵羊糖蛋白激素α亚基的多克隆抗体进行免疫细胞化学染色，以及用与α亚基mRNA互补的反义寡核苷酸进行原位杂交，结果表明糖蛋白激素的共同α链在结节部特异性细胞中表达。针对β亚基的抗体未能在这些细胞中检测到任何已知的垂体糖蛋白激素β链。在成年绵羊结节部特异性细胞中糖蛋白α亚基的证实支持了先前已有的证据，即这些细胞确实分泌一种或多种糖蛋白激素。关于大鼠和仓鼠中促甲状腺激素β样免疫反应性，有人可能推测结节部特异性细胞是一种多能细胞类型，在基础条件下分泌活性较低。进一步的研究应证实这一假设，即这些细胞中预先存在的mRNA池可用于生理或药理刺激后糖蛋白激素的持续翻译。
