Saturday, April 28, 2007

Monster Update: Week 05

Deep in the bowels of Stef's uterus, the Monster is growing at a furious pace. At this point its about the size of a sesame seed (pictured, not actual size), and it looks more like a tiny tadpole than a human. The Monster is now made up of three layers — the ectoderm, mesoderm, and endoderm — that will later form its organs and tissues. The cells are forming for the major organs, including its kidneys and liver, and its neural tube is beginning to develop. This neural tube — from which the Monster's brain, spinal cord, nerves, and backbone will sprout — develops in the top layer, called the ectoderm. This layer will also give rise to skin, hair, nails, mammary and sweat glands, and tooth enamel. The Monster's heart and circulatory system begin to form in the middle layer, or mesoderm. (This week, in fact, its tiny heart begins to divide into chambers and beat and pump blood.) The mesoderm will also form the Monster's muscles, cartilage, bone, and subcutaneous (under skin) tissue. The third layer, or endoderm, will house its lungs, intestines, and rudimentary urinary system, as well as its thyroid, liver, and pancreas. In the meantime, the primitive placenta and umbilical cord, which deliver nourishment and oxygen to the Monster, are already on the job.

Text adapted from Baby Center.

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