Purpose: To visualize the three-dimensional organization of primary lens fiber cells.
Methods: The gene for Green Fluorescent Protein (GFP) was introduced into the lens vesicle using two different vector systems: a replication deficient adenovirus or an expression plasmid. Injected embryos were allowed to develop for several days and then were examined by confocal microscopy.
Results: Injection of either vector resulted in GFP expression in primary fiber cells. GFP-expressing cells were heterogeneous in shape and length. Some regions of the fibers were varicose, with diameters >10 microm; regions between the varicosities were often extremely thin, with diameters of <2 microm. No differences in the morphologies of GFP-expressing cells were noted between adenovirus and plasmid-injected lenses, suggesting that the irregular, undulating, appearance of the primary fibers was not the result of viral infection. Three-dimensional reconstruction of primary fiber cells revealed that, by E6, the posterior tips of the fibers had detached from the lens capsule. The anterior fiber tips remained in contact with the overlying epithelium for 1 to 2 additional days, demonstrating that the formation of the anterior and posterior sutures was asynchronous.
Conclusions: The three-dimensional cellular organization of GFP-expressing cells is consistent with previous analyses of fiber cell morphology in the embryonic nucleus of adult human and bovine lenses. The present data confirm that the disorganized appearance of primary fiber cells observed in adult lenses is largely a reflection of developmental processes rather than a consequence of aging.