GDNF and Hyperglycemia: TUNEL assay in vivo revealed apparent increased cell apoptosis and collapse of nephrons in fetal and newborn kidneys of the hyperglycemic group, and confocal morphological observation demonstrated ureteric bud as unable to invade metanephric mesenchyme associated with enhanced GDNF, EGR-1 and ERK-2 expression on E15 in hyperglycemia-induced fetal nephropathy.