7 days old indian runner duck egg being candled to observe the development of the embryo. the light penetrates the egg

duckling observation development yolk duck egg veins incubator embryo lamp shining poultry eggbearing incubation heart observing inside developing darkness incubated candling brooding brooder light breeding red optical hatchling growing new unborn vasculogenesis research lab bird natural farm runner indian breed closeup yellow domestic brightly