Expression of transforming growth factor β in the embryonic avian lens coincides with the presence of mitochondria

During their maturation, lens cells lose all membrane bound organelles, including mitochondira. In chicken embryos this process begins in the central lens fibers beginning around embryonic day 12 (E12). Transforming growth factor β (TGFβ) is a multipotent growth modulator thought to play a role in numerous developmental processes. TGFβ1 has been localized to mitochondria in rat liver cells and muscle cells. In the present study, we examined the expression of TGFβ isoform mRNAs and proteins during chicken embryonic lens development. PCR analysis demonstrated TGFβ2 and TGFβ3 trasncripts in the lens epithelium and fibers throughout pre‐ and post‐hatching development. TGFβ isoforms were detected throughout the lens epithelium and fibers early in development (E6). However by E19, the distribution of TGFβ2 and TGFβ3 transcripts and proteins coincided with regions of the lens that contained mitochondria. In addition, intense TGFβ staining was observed in the basal portions of the equatorial epithelial cells, a region with abundant mitochondria. Transcripts for TGFβ1 and TGFβ4 were not detected in any tissue or time frame examined. Similarly, no immunostaining for TGFβ1 was observed. ©1995 Wiley‐Liss, Inc.