Getting ready to be a mother

by Carolyn Conant Van Blarcom

Fig. 6.—Diagram indicating process of cell division.

Returning to the ovum which meets a spermatozoon in the course of its journey down the tube, we find that as soon as a spermatozoon enters an ovum it disappears and is completely absorbed, and, as the ovum in turn is instantly possessed of new powers, through the presence of the male cell, the result of this union is an entirely new cell. But instead of continuing its existence as a single cell, the fertilized ovum divides into two cells; these two into four; the four into eight and so on until a clustering mass of cells is formed which looks something like a mulberry. If you will look at Fig. [6] you will see what happens as this cell division progresses and also that in time the cells rearrange themselves in such a way as to leave a space in the center of the mass so that it becomes a little sac with a cluster of cells at one point, which hangs toward the center, called the internal cell mass. This will interest you because it is from cells at one point in this little cluster that the baby begins to develop, together with the cord, bag of waters and afterbirth, to be described later.

While these changes are taking place, the entire mass is being carried slowly down the tube toward the uterus by the sweeping motion of the soft little hairs on the lining of the tube. It is steadily growing, and by the time it reaches the uterus the mass is about the size of the head of a pin. As you will remember, the lining of the uterus prepares each month to receive the fertilized ovum, becoming soft and thick. The cell mass floats around for a little while after it reaches the uterine cavity and then resting at some point, sinks down into the soft lining and is completely buried.

From now on the cells which compose the mass rapidly increase in number and very shortly cease to be all of one kind. These different kinds of cells rearrange themselves and grow in such a manner that some of them begin to form the different parts of the baby’s body and others develop into two thin membranes that finally enclose the baby in a double sac. He is attached to the inner surface of the sac; the space which he does not occupy is filled with fluid and the sac itself is attached to the uterine lining at the point where the cell mass happened to stop and bury itself.

This sac is what you have heard called the “bag of waters,” but the doctors refer to it as the membranes. As it enlarges and pushes out into the uterine cavity it still consists of two thin membranes except where it is attached to the uterus, at which point it grows into a thick, spongy mass of blood-vessels. These blood-vessels divide and branch out in a tree-like fashion and burrow into the uterine wall. As you will see later, it is through this mass of branching blood-vessels that the baby virtually eats and breathes and gives off waste materials during the nine months of his life within the uterus. The doctors refer to the mass as the placenta but you have heard it called the “afterbirth,” because it is expelled after the baby is born.

Fig. 7.—Diagram showing the developing baby, at an early stage, with cord, membranes and placenta, within the uterine cavity.

As the baby’s development advances the part by which he is connected with the placenta lengthens out into what is called the umbilical cord. There are blood-vessels in this cord through which blood constantly flows back and forth, carrying nourishment to the baby from his mother and waste matter from his little body to the placenta where it is taken up by her blood. But this exchange of materials takes place through thin membranes and consequently the blood of the mother and baby never mingle. Fig. [7] will give you an idea of how the sac of membranes, with the baby hanging inside, grows out into the uterine cavity; how at the point where the membranes are attached to the uterus the blood-vessels have developed into the thick, spongy placenta and how the baby is connected with it by means of the cord. In Fig. [8] you may see how the baby changes in appearance as the weeks of pregnancy go by. At the end of the fourth month he really looks quite like the baby that we are so eagerly preparing for.

If we follow his development within the uterus month by month, we find that by the end of the first lunar month, or fourth week, the baby’s body is about ½ inch long and looks about as is suggested in the third little outline in Fig. [8].

At the end of the second month, or eighth week, his head is fairly well shaped; bones are beginning to develop, webbed hands and feet are formed and the little body is about 1 inch long.