[Expression of mutant genes in mouse aggregation chimeras. 4. The aphakia gene].

Analysis of aphakia (ak) gene expression in ak/ak C/C in equilibrium +/+ c/c experimental chimaeras has shown that the ak gene acts in the lens rudiment cells blocking it differentiation. In the lens of 12 day old ak/ak C/C in equilibrium +/+ c/c chimaeric embryos undifferentiated ak/ak cells were present among the normally differentiating fibres. In 14 and 18 day old chimaeric embryos and 20 day old chimaeric mice ak/ak cells are located under the lens epithelium and the capsule of posterior lens half. In the locations of ak/ak cells on the posterior lens surface capsule breaks resulted in the extrusion of lens material into the secondary eye cavity. In all studied chimaeric embryos the lens structure is more similar to that in the normal embryos, than in ak/ak embryos. This suggests that in the developing chimaeric lens ak/ak cells are sorted out as the development proceeds. The proliferation rate of +/+ cells appears to be higher than that of ak/ak cells.