THE HYGEINE OF MARRIAGE: CONCEPTION AND CHILDBIRTH – FERTILIZATION AND THE PROCESS OF THE DEVELOPMENT OF A CHILD
The process of the development of a child is very complex, and only a few stages can be mentioned here. Once the single fertilized cell is formed, growth by cell division goes on until a microscopic hollow spherical mass of cells is formed. One side of this sphere now collapses against the other, as one side of a hollow rubber ball may be pushed against the other side, and thus a two-layered cell mass is formed. From parts of these two layers a third middle layer is formed, and from these three layers all parts of the body develop.
In the meantime, the spherical mass of cells has become 45 embedded in the wall of the uterus. From it there develop: (1) the amnion and chorion, two membranes which later surround the growing body and enclose the fluid by which it is covered; (2) the placenta, which is firmly attached to the wall of the uterus and provides a means by which the blood of the mother may communicate with the blood of the child; and (3) the umbilical cord, which consists largely of vessels carrying blood to and from the body of the child and the placenta. It may be stated here that the blood of the child and the blood of the mother do not mix, but are separated by this permeable tissue through which food and oxygen diffuse from the mother's blood into the child's and wastes diffuse from the child's blood into the mother's.
During the time required for the fertilized ovum to develop into a completely formed miniature human being, the growing organism is known as an embryo. After this stage is reached—which requires about eight weeks—the organism is known as the fetus. The fetus is readily recognized as a miniature human being. It lies within the uterus, usually with the head down, and is surrounded by a clear, somewhat viscous fluid enclosed within the amnion and chorion. The fetus goes on to complete development, which is reached about two hundred and eighty days after fertilization.
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