At About 21 Days, Two Ridges Appear in the Embryo

question 45

Multiple Choice

At about 21 days, two ridges appear in the embryo and fold to make up the neural tube, which develops into the

• A) nails, hair, and teeth.
• B) digestive system, liver, and pancreas.
• C) brain and spinal cord.
• D) circulatory system, muscles, and skeleton.

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Definitions:

Estrogen Levels

The concentration of estrogen hormones in the body, which are critical for the development and regulation of the female reproductive system and secondary sexual characteristics.

Osteoporosis

A disease characterized by low bone mass and deterioration of bone tissue, leading to increased bone fragility.

Bone Matrix

The intercellular substance of bone tissue, consisting of collagen fibers and ground substance, which provides rigidity and supports bone cells.

Collagen Development

The process by which collagen, a primary structural protein in the body, is synthesized, assembled, and organized into a functional form.