eggs are candled to observe the development of the embryo. the air pocket and veins are clearly visible inside the egg.

baby heart animal duckling duck egg veins incubator embryo lamp shining poultry observation incubation observing developing darkness incubated candling brooding brooder breeding microscopic red optical hatchling growing unborn vasculogenesis biology research lab bird natural farm agriculture runner indian breed eggbearing closeup yellow domestic brightly