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Posts Tagged ‘Human Development’

Building on the quotes from medical and biological texts posted below yesterday, there is a need to answer some common mischaracterizations of exactly what a human embryo and fetus is, and what it is not. Some fundamental biology will clear up the confusion.

A commenter on the post No Handicapped Allowed has this to say,

“If I were married, and my wife were pregnant, I would want to get the amnio test, but ultimately I would have to respect her choice if she declined. I would fully support her decision to abort if there were clear (not maybe 1%) evidence of Down’s syndrome, or particularly of anancephaly. I don’t think of that as killing a baby. I think of it as removing tissue that will grow into a baby with severe disabilities, or even with no brain at all. Again, if she declined, I would have to respect her decision. The body often spontaneous miscarries such tissue — I have no problem with human intervention if the body doesn’t recognize the problem in time.”

It’s an understandable position until one sees the developmental stages.

The commenter mentions amniocentesis and the baby at that stage being mere tissue that has potential to become a baby in the future.

Typically, amniocentesis is performed between 16-20 weeks of development. By then the baby has developed substantially with all of its organ systems in place. When the term ’tissue’ is tossed around, it is almost universally used incorrectly.

16 Weeks Photo: MedicineNet.com

A Primer On the Hierarchy of the Human Body’s Organizational Levels:

Cells. There are approximately 200 distinctly different types of cells that comprise the human body.

Tissues. Different types of cells aggregate to form specialized functions and are called tissues. The human body is comprised of four main tissue types: Epithelial, Connective, Muscle, Nerve.

Organs. These are composed of two or more tissue types to perform special functions. Examples: Stomach, intestines, pancreas, liver, heart, etc.

Organ Systems. These are two or more organs that act in a coordinated fashion to perform a common function. For example the digestive system is composed of several organs, including the stomach, pancreas, sall and large intestines, etc., whose coordinate function is the digestion and absorption of nutrients.

Organism. This is the whole and complete animal, made up of all the organ systems functioning as a coordinated whole.

See these video and 4-D ultrasounds of developing embryos and fetuses at The Endowment for Human Development.

20 Weeks Photo: MedicineNet.com

It must be stressed, however, that even in the single-celled stage of development, the zygotic stage, there exists a brand new human organism, whole and complete in form and function for that developmental stage.

The same holds true for every stage thereafter. That’s because even at the single-celled stage, the zygote is intrinsically ordered toward mature organismal development and is proceeding along that trajectory. At birth, the baby lacks full maturational development, and will not attain such until adulthood. This developmental reality renders all argument to the contrary an expression of whim, of personal desire, with no bearing on the biological reality of organismal development.

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