Determination of eggs fertility in poultry (egg tract)
In order to determine whether the eggs are fertile or not they are cancelled at about five (5) days.
This involves passing a strong light in the eggs while looking at it, if the eggs are fertile the developing
embryo as a spick with a spider web light network of blood vessels will be seen. If a fertile egg has stop developing it will be seen as a dark spot with a red rim above it.