Transforming growth factor β mRNA and protein expression in the ovary of the chicken embryo.

The expression pattern of transforming growth factor beta (TGF beta) isoforms in chicken embryo gonads was studied at 6-10 days of incubation. TGF beta 2 mRNA was expressed predominantly in the cortex of the left ovary from day 8 of incubation onwards. TGF beta 3 mRNA was not detected at any of the stages studied. Similarly, immunofluorescence for the TGF beta protein revealed that at day 9 it was located throughout the cortex of the left ovary and in the medulla of both the left and right ovaries. The presence of phosphorylated Smad2 in the nuclei of these regions suggests that TGF beta signaling is most likely active at this developmental stage. Culturing the left ovary in a TGF beta 1-supplemented medium induced a shift of cortical structures toward the medulla, suggesting a role for TGF beta in the morphogenesis of the female gonad in chickens.