EXPRESSION OF TGF-BETA-S AND TGF-BETA TYPE-II RECEPTOR MESSENGER-RNASIN MOUSE FOLLICULOGENESIS - STORED MATERNAL TGF-BETA-2 MESSAGE IN OOCYTES

The present in situ hybridisation study describes expression of TGF-nl , TGF-beta 2, TGF-beta 3, and TGF-beta type II receptor mRNA during fo llicular development, and the temporal pattern and abundance of TGF-be ta 2 transcripts in early pre-implantation embryos. TGF-beta 1 hybridi sation signals were most prominent in the outer granulosa cell layers of the post-antral follicles and in the corpus luteum, whereas strong expression of TGF-beta type II receptor mRNA was confined to thecal ce lls. Weak TGF-beta 3 mRNA expression was observed in all major cell ty pes of pre- and post-antral follicles. Most notably, the very strong T GF-beta 2 hybridisation signals which were detected in developing oocy tes declined rapidly following fertilization. Although still abundant in two-cell embryos, TGF-beta 2 hybridisation signals were barely dete ctable in four- and eight-cell embryos. These findings, and the presen ce of specific sequence motifs in the 3' untranslated region of TGF-be ta 2 mRNAs, suggest that TGF-beta 2 trancripts are stored as maternal messages. (C) 1994 Academic Press, Inc.