Page 97 - The Miracle of Human Creation

THE CREATION OF A HUMAN BEING FROM A CELL

throughout its whole life. The outer group of cells (trophoblast), is com-
posed of the cells that assist the human being in its life in the mother's
womb, that is, for nine months until its birth.
The inner cell mass separates itself from the outer group of cells that
will serve it throughout the nine months. The remaining region will beco-
me the umbilical cord providing the connection between the embryo and
the placenta that will develop later.
At about the same time that the placenta begins to form, the inner
cell mass flattens and develops into three layers of cells in what is called
the "embryonic disc". The three types of cell layers are the ectoderm, the
mesoderm, and the endoderm. In a process called differentiation, cells
from each layer move to certain areas of the embryonic disc and then fold
over to form tubes or clusters. These tubes and clusters develop into vari-
ous tissues and organs of the body. 23
Cells from the outermost layer, the ectoderm, form the brain, spinal
cord, the sense organs and the lens of the eye. Moreover, this layer will
form the epidermis, the sweat glands, tooth enamel, hair and nails. The
innermost layer of the embryo (the endoderm) will cause the develop-
ment of the organs that compose the digestive and respiratory systems (li-
ver, lungs, pancreas, etc.) and the related glands (thyroid, thymus, etc.).
The third layer (the mesoderm) is formed between these two layers. From
this layer are formed the heart, muscles, bones, tendons, kidneys, glands,
blood vessels, and reproductive organs. The lymphatic vessels and the
epithelia (surface, or lining, tissues) which cover the most internal and ex-
ternal surfaces of the body and its organs also develop from this layer. The
cells which compose all the tissues of the body are formed from these
stem cells which develop from one of these layers.
It is very important to think about the meaning of the last sentence
of the above paragraph, and to consider well the significance of what it
says, because only in this way can we begin to conceive of the extraordi-
nary development of a human being. The fact that all the elements that
constitute the human body (organs, tissues, systems, blood vessels, blood,
etc.) develop from the three kinds of layers that make up the embryo will

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