The part of human hair fiber, called the medulla, is an assembly of cells located at the center of the hair fiber. In humans. Only very thick hair appears to have a continuous line of medullary cells. .. most humans have a medulla which is usually not continuous through the strand. And some humans have no medulla present in their hair.
However. With reference to other mammals.. most all have hair (fur) that contains quite a strong medulla. Perhaps the medulla serves as a strengthening or protective function in the hair. And, we all know that hair strength and resistance differs from person to person. B
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