Expression of glial fibrillary acidic protein and vimentin in mouse lens epithelial cells during development in vivo and during proliferation and differentiation in vitro: comparison with the developmental appearance of GFAP in the mouse central nervous system.

Analysis of glial fibrillary acidic protein (GFAP) and vimentin in mouse lens epithelial cells (MLEC) during ontogenesis revealed a two-step developmental expression similar to that observed in astrocytes. Vimentin was first immunostained at E11 corresponding with the closure of the lens vesicle, whereas GFAP was detected only after a further 7 days (E18); this protein appeared simultaneously in the mouse lens and CNS. In the latter case, it was present in the hypothalamic tanycytes and spinal cord. This similarity in the timing of appearance of GFAP in the non-neural MLEC and in fetal astrocytes suggests a common mechanism for its expression in tissues of different embryological origin. However, it has previously been observed that, in contrast to the situation in astrocytes, GFAP disappears from differentiating MLEC in vivo. We have shown that in vitro this protein also disappears rapidly from MLEC in the presence of fetal calf serum (FCS). However, the use of mouse serum instead of FCS inhibited the migration of MLEC out of the explant, and in these cells GFAP persisted.