Development of actin polygonal arrays in rabbit lens epithelial cells

In searching for a clue to the role of actin filament bundles organized into polygonal arrays, or geodomes, in lens epithelial cells, we examined several physical events occurring in the young rabbit lens which may initiate their formation. We used NZW rabbits between the ages of 24 days gestation and 50 days postnatal. Data were obtained from TEM, SEM and fluorescence microscopy. Parameters measured were lens weights, apical surface areas of cells in epithelial whole mounts, epithelial cell thickness, and timing of eyelid opening, breakdown of the tunica vasculosa lentis (TVL) and formation of the ciliary zonules; these findings were correlated with the first signs of development of the arrays. Polygonal arrays formed slowly beginning at one to two days after birth, and with advancing time these thickened and made more numerous connections with the lateral plasma membranes. Development of the arrays was not correlated with onset of vision or disappearance of the TVL or a sudden increase in cell area, since these events occur postnatally at about 9-10 days, nor with the development of zonular fibers since these are already in place at 24 days of gestation. Only lens weights showed a dramatic increase between 24 days gestation and birth. It is surmised that the expanding lens mass may be involved in some way in signaling the organization of actin filaments into geodomes.