Postdoc University of California, Berkeley, United States
Introduction:: The ocular lens is an avascular multicellular organ, which grows continuously during the lifespan of the animal. Studies on the cellular organization of postnatal lenses have been carried out ex vivo on sections of enucleated lenses using light and electron microscopy. Here, we have visualized the lens cellular organization of live mice in vivo at different ages by using two photon fluorescence microscopy and adaptive optics.
Materials and Methods:: We employed direct wavefront sensing to measure and correct aberrations in two photon fluorescence microscopy measurements of cellular organization deep inside the anterior part of the lens in vivo in live mice. We employed transgenic mice that express tdTomato fluorescent proteins in lens cell membranes and carried out longitudinal imaging of lens fiber cellular organization of same mice at different ages.
Results, Conclusions, and Discussions:: We obtained significant improvements in signal, contrast, and spatial resolution of lens cell images up to >700 μm depth inside the lens in vivo. We observed novel morphological features such as anterior voids, enlarged vacuoles in fiber cells, and inhomogeneous organization of fiber cells with depth in different regions up to near the lens core that have not been reported in the previous ex vivo studies. We unexpectedly observed large ‘abnormal cavities’ in the deeper regions of these live lenses. The longitudinal studies of lens images revealed the incorporation of layers of new fiber cells as well as the retention of size and shape of the anterior voids at the different ages.
Taken together, non-invasive longitudinal in vivo imaging of lens morphology using two photon fluorescence microscopy and adaptive optics revealed novel cellular information about lens suture formation and alterations of lens fiber cell morphogenesis such as unique voids that might reflect fiber cell subcellular structures in the lenses of live animals at different ages and be related to the inward flow pathways of the lens internal circulation.