Bruno has to have part of his bone tested by his doctor. The doctor explains that they will place a needle into the innermost part of the bone to draw out a thick jelly-like substance. What layer of the bone is MOST likely being tested in this process?

The innermost part of a bone contains bone marrow, a soft, thick tissue that can be drawn out with a needle. The procedure described is therefore testing bone marrow. The periosteum covers the bone’s outer surface, while cancellous and compact bone are types of bone tissue.

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