Genetic, cellular and molecular perspectives on the morphogenesis, neurogenesis and regeneration of the retina in vertebrates.

Abstract

The transformation of the embryonic neuroepithielium into the mature retina requires the spatial and temporal coordination of gene expression, morphogenetic movements and neurogenesis. The eventual formation of a functional retina and the ultimate establishment of normal visual function relies on the success of these early events. Using anatomical, histochemical and molecular biological techniques, these studies examine three aspects of retinal development. The first study examines the role of Pax2 in retinal morphogenesis in <italic>Kidney and Retinal Defects</italic> (<italic>Krd</italic>/+) mice, and characterizes changes in morphology and Pax2 protein expression during embryonic development that result from the deletion of the <italic>Pax2</italic> locus. This study demonstrates that the congenital malformations in the optic disc and retinas in these animals arise from early malformations in the optic stalk and retina. The second study focuses on the cellular basis of ongoing neurogenesis in the retinas of goldfish and uses long-term systemic exposure to bromodeoxyuridine (BrdU) to identify slowly dividing cells in the retinas of goldfish. This study shows that the cellular origins of ongoing rod photoreceptor neurogenesis in the mature retinas is the same as during larval development. The third study considers the role of the growth factor IGF-I in growth-associated and injury-induced neurogenesis in the retinas of goldfish. These studies describe the molecular cloning, sequence analysis and gene expression of the goldfish homologues, of the insulin-like growth factor-I (IGF-I) and its receptor (IGF-IR) in the normal and injured/regenerating retinas of goldfish.