To understand why there are eggs with two yolks, it is essential to know how an egg is formed.
The yolks are produced from the nutrients ingested by the hens and allow, within a week, small one-millimeter follicles found in the ovary to grow into the shape of a fully developed bud of about 25 millimeters.
When they grow to this size, each bud will travel through a canal called the oviduct that connects the ovary to the uterus. This process can last a whole day and it is during this period that the rooster can fertilize the hen so that a chick is born. In the central part of this channel is when the fiber that surrounds the yolk is formed and that in cooking is known as clear. When the inner part of the egg is completely formed it reaches the end of this duct and enters the next organ, the uterus; This is where the solid structure that surrounds and protects the egg, the shell, will be formed.
How then do eggs with more than one yolk emerge?
It is not usual for this phenomenon to happen, although it is not something very strange. Eggs with more than one yolk can be produced for two reasons. On the one hand, if more than one bud is expelled from the ovary, they will go their usual way until they are encapsulated together within the same shell.
Or it may happen that one yolk has been blocked in the oviduct and that when the next one goes down, they go down together until the egg is completely formed, thus obtaining an egg with more than one yolk.
This phenomenon usually occurs due to hormonal problems that are more frequent in young hens or in old hens that are reaching the end of their reproductive cycle. And although the mortality rate of embryos that share eggs is very high, the situation may arise in which both survive, thus being born two chicks from the same egg.
Double eggs are totally safe for human consumption and do not pose any risk to our health. In fact, they have higher levels of vitamin A and choline, an essential nutrient.
Source of superstition
Traditionally, eggs with two yolks have been involved in various superstitions. The most common was the belief that this specific event brings good luck; but in addition, the fact of finding a double yolk was related to events as diverse as upcoming weddings or the birth of twins.
