HAVE you ever given thought to how an egg is made? It is quite a complicated as well as orderly process, a fascinating one.
The development of an egg takes place in the ovary and oviduct. Chickens have only one ovary, on the left side. Certain wild birds, however, have two ovaries and oviducts. The ovary in a chicken might be likened to a bunch of grapes, with the many ova in various stages of development. The most ova ever found in one chicken was 3,065, and the greatest number of eggs any one chicken laid in her lifetime, as far as observed by man, is said to have been 1,515 in eight years.
The egg-producing process of a chicken takes about twenty-four hours. In less than an hour after a chicken has laid an egg another yolk has reached its full size, at which time it consists of six layers. In wild birds the sixth layer depends upon the presence of a male bird. If no male bird is on hand the female cannot produce her egg. Domestic fowl, though, can keep on laying eggs without ever seeing a rooster.
Can there be any purpose in this? Indeed there is. The purpose served by wild birds in laying eggs is the reproduction of their species, and so the presence of the male is required for mating. But domestic chickens also lay eggs for human consumption, and for this purpose a male bird is not needed.
Once the yolk has been fully formed or is ripe, it drops off the ovarian stem into the oviduct or egg tube, which consists of several sections. In the first section, known as the infundibulum, the egg is fertilized if the chicken has mated. Its stay in this section is but a matter of minutes; then it passes to the next section, the magnum. As the egg moves through this section the albumin is added, layer upon layer, four in all, a process that takes about four hours. By then it has also reached the next section, the isthmus, where two membranes, an inner and an outer, are added to cover the albumin layers.
These latter two membranes are completed in about an hour and ten minutes, then the egg reaches the uterus or shell gland, where it tarries for some nineteen hours. When the outer and inner membranes were first added they fit snugly over the egg, but soon they loosen up and so in the uterus the first five hours are consumed in filling out the membranes with water and minerals, a process termed “plumping” the egg. Then for the next fourteen hours several layers of eggshell are added. After that the cuticle or skin is supplied, giving the egg its characteristic color. The egg then moves on to the vagina and is expelled by the chicken.
By now you may well be asking, Who instructed the chicken in the making of an egg? How does she know how long the egg has to be in each section?
Furthermore, the producing of an eggshell presents quite a challenge to a chicken. The blood of a laying chicken at any one time contains only 25 milligrams of calcium (non-layers and roosters have only about one-third as much), yet while producing an eggshell the chicken uses 125 milligrams per hour. Where, then, does she get this extra calcium? The original source, of course, is the food she eats, the chicken extracting the calcium from her intestines. But still she is unable to absorb calcium from this source as quickly as she needs it.
So what does she do? She draws it from calcium reserves found in the ‘medullary bones’ located within the cavities of most of her regular bones. These secondary bones are not found in male chickens or in chickens too young or too old to lay eggs. This system is so efficient that a hen can mobilize as much as 10 percent of the total calcium in her bones in one day if her diet is very low in calcium. However, if her diet continues low she cannot keep this up and so first compensates by laying eggs with thinner shells. If a serious shortage of calcium persists, the chicken quits laying altogether rather than laying eggs without shells. Who taught her how to grow extra bones so as to have sufficient calcium for eggshells?
It is indeed interesting to note the facts of how a chicken egg is made. Truly there is evidence in it of wisdom and design. It adds its testimony to countless other wonders of visible creation that there is indeed an all-wise and almighty Creator, whom the Bible identifies as Jehovah God.
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