As you can see, along the length of the hair, there are three main parts called the bulb, the root and the shaft.

如你们所见，顺着头发的长度可以分为三个主要部分，分别是毛囊、毛根和毛干。

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The bulb acts rather like a cap—it encloses the end of the hair in the head.

毛囊的作用有点像帽子——它将发根紧紧地附于头皮上。

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The hair is formed from cells just above the bulb, which also give rise to concentric zones of differentiated epithelial cells destined to form the inner and outer root sheaths.

毛球之上的细胞形成毛发，产生由分化的表皮细胞构成的同心环状区，形成内根鞘和外根鞘。

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At the base of the hair root is a small ball-like formation called a bulb.

VOA: special.2011.04.05

Marjorie wore her quilted bathrobe, and her bulb of short graying hair was lopsided from lying in bed.

NEWYORKER: The Visitor