Blood spots;
The yolk is formed in the follicular sac by the deposition of continuous layers of yolk material. Ninety-nine percent of the yolk material is formed within the 7-9 days before the laying of the egg. When the yolk matures, the follicular sac ruptures or splits along a line with few, of any, blood vessels. If any blood vessels cross the stigma, a small drop of blood may be deposited on the yolk as it is released from the follicle. This causes most blood spots in eggs. After the yolk is released from the follicle, it is kept intact by the vitelline membrane surrounding it. The release of the yolk from the ovary is called "ovulation."
Very edible, so don`t worry about them. They will go away, but may return at times. Eggs with blood spots are candled by egg farms and removed to be sold for use in bakeries, etc. You`ve been eating them all along and didn`t know it. Won`t hurt a thing......Pop