McWilliams D, Boime I
Endocrinology. 1980 Sep;107(3):761-5. doi: 10.1210/endo-107-3-761.
Previous histochemical studies identified human placental lactogen (hPL) in the syncytial layer rather than in the cytotrophoblast cells of human placenta. However, these studies failed to rule out the possibility that de novo synthesis occurred in a cell type distinct from that in which the highest steady state level is accumulated after intercellular transport. To address this point, localization of placental mRNA in trophoblasts was attempted by the technique of in situ hybridizaton. Term placental sections were incubated with [3H]cDNA transcribed from sucrose gradient-purified hPL mRNA. Slides were stained, fixed for autoradiography, and examined under the light microscope. The syncytial layer was covered with silver grains. The amount of this radioactivity was greatly reduced when placental fragments were incubated with globin [3H]cDNA or if hPL [3H]cDNA was hybridized to sections of human tonsil tissue. In addition, the amount of silver grains was greatly reduced when the sections were prehybridized with labeled probe. These results suggest that hPL is synthesized in the syncytial layer of placental villi and that the appearance of hPL in this region was not the result of intercellular transport.
以往的组织化学研究表明，人胎盘催乳素（hPL）存在于合体层，而非人胎盘的细胞滋养层细胞中。然而，这些研究未能排除这样一种可能性，即从头合成发生在一种与细胞间转运后积累最高稳态水平的细胞类型不同的细胞类型中。为了解决这一问题，通过原位杂交技术尝试对滋养层细胞中的胎盘mRNA进行定位。将足月胎盘切片与从蔗糖梯度纯化的hPL mRNA转录而来的[3H]cDNA一起孵育。玻片染色、固定以进行放射自显影，并在光学显微镜下检查。合体层覆盖着银颗粒。当胎盘碎片与珠蛋白[3H]cDNA一起孵育时，或者当hPL [3H]cDNA与人扁桃体组织切片杂交时，这种放射性的量会大大减少。此外，当切片与标记探针进行预杂交时，银颗粒的量也会大大减少。这些结果表明，hPL是在胎盘绒毛的合体层中合成的，并且该区域中hPL的出现不是细胞间转运的结果。
