Читать книгу The Mother and Her Child - Lena K. Sadler - Страница 23

The fertilized ovum remains in the tube for about one week, when it slowly makes its way down into the uterus, all the while rapidly undergoing segmentation or division. It does not grow much in size during this first week, but divides and subdivides first, into two parts, then four, then eight, then sixteen and so on, until we have a peculiar little body made up of many equally divided parts, and known as the "Mulberry Mass" (Fig. 1). The blending of the sperm and ovum has been perfect, the division of the original body multitudinous.

While this division of the united sex cells is progressing, a wonderful change is also taking place in the inside lining of the uterus. Instead of the usual thin lining, it has greatly thickened and has become highly sensitized, and as the ovum enters the uterus from the fallopian tube, this sensitized lining catches it and holds it in its folds—actually covers it with itself—holding the precious mass much as the cocoon, you have so often seen fastened to the side of a plant or leaf, holds its treasure of life.

Just as soon as the new uterine home is found the baby heart begins to make its appearance, as also do many other rudimentary parts. By the end of the third week, our round mass has flattened and curved and elongated, and the nervous system and brain begin to develop, while the primitive ears begin to appear. At this time, the alimentary canal presents itself as one straight tube which is a trifle larger at the head end. And it is interesting to note that at this early date, even the arms and legs are beginning to bud and push out from the body.