SYNCYTIOTROPHOBLASTIC LOCALIZATION OF THE HUMAN GROWTH-HORMONE VARIANT MESSENGER-RNA IN THE PLACENTA

The hGH/hCS genes, clustered on chromosome 17 in the 5' to 3' order GH -N, CS-L, CS-A, GH-V and CS-B, show a high degree of sequence identity . The expression product of the GH-V gene is the placental growth horm one, which replaces pituitary GH in maternal blood throughout pregnanc y. By means of mRNA competitive hybridization using P-32-labelled and unlabelled 30 bases long oligonucleotides, we first optimized specific hybridization conditions. In situ hybridization was then performed to locate the GH-V mRNA encoding placental growth hormone. The hGH-V gen e appears expressed in the placental syncytiotrophoblast. Unlike the C S-A and CS-B genes (both encoding hPL) which are expressed uniformly i n the syncytiotrophoblast, the GH-V mRNA is located in a few syncytiot rophoblast cells only.