Hoshina M, Boothby M, Boime I
J Cell Biol. 1982 Apr;93(1):190-8. doi: 10.1083/jcb.93.1.190.
Probes derived from clones bearing cDNAs corresponding to the alpha subunit of human chorionic gonadotropin (hCG) and human placental lactogen (hPL) were used to localize their respective mRNAs cytologically in sections of first trimester and term human placenta. hPL mRNA was exclusively localized to the syncytial layer, hCG alpha mRNA was found in the syncytial layer and also in some differentiating cytotrophoblasts. Hybridization was specific because no signal was observed when labeled pBR322 was hybridized to placental sections or when the placental probes were hybridized to sections of human tonsils. In addition, RNA in placental interstitial cells did not hybridize with hCG alpha and hPL probes. Hybridization with the hCG alpha probe was much greater in first trimester than in term sections, whereas hPL signals were comparable in both first trimester and term placentae. Syncytial formation proceeds through cellular intermediates of cytotrophoblastic origin, and the data suggest that transcription of the hCG alpha gene is initiated before the completion of syncytial formation. In contrast, hPL mRNA synthesis starts later in trophoblast differentiation, likely after the stage of syncytial formation. The data also suggested that hCG alpha mRNA synthesis becomes attenuated but that hPL is transcribed at a rather constant rate during placental development.
从携带与人类绒毛膜促性腺激素（hCG）α亚基和人胎盘催乳素（hPL）相对应的cDNA的克隆中获得的探针，用于在孕早期和足月人胎盘切片中对它们各自的mRNA进行细胞学定位。hPL mRNA仅定位于合体层，hCGαmRNA则在合体层以及一些分化中的细胞滋养层细胞中被发现。杂交具有特异性，因为当标记的pBR322与胎盘切片杂交时，或者当胎盘探针与人类扁桃体切片杂交时，均未观察到信号。此外，胎盘间质细胞中的RNA不与hCGα和hPL探针杂交。与hCGα探针的杂交在孕早期切片中比在足月切片中要强得多，而hPL信号在孕早期和足月胎盘中相当。合体形成通过细胞滋养层来源的细胞中间体进行，数据表明hCGα基因的转录在合体形成完成之前就已开始。相比之下，hPL mRNA的合成在滋养层分化后期开始，可能在合体形成阶段之后。数据还表明，hCGαmRNA的合成减弱，但hPL在胎盘发育过程中以相当恒定的速率转录。
