The human eyes are protected and lined by eyelashes. Precisely, each eyelid has a single row of eyelashes. A single eyelash is anchored by a root hair plexus to the eyelid. This aids in the reflex action of the eyelid to close when a foreign particle enters it. The functions of eyelashes are very similar to the whiskers of a cat as they are very sensitive to touch.
On closer look, one finds that the eyelashes of the upper eyelid are longer, and have a propensity to curve in an upward direction. They may grow up to ten millimeter in length. The eyelashes of the lower eyelid are relatively shorter and do not tend to curve. They are rather stumpy, and just stick out. Each eyelash has a three phases of growth cycle and is similar to hair in the other parts of the body.
The first phase is the Anagen phase, where the hair grows actively for a period of thirty to forty five days. The next phase is the Catagen phase where the eyelash stops its growth, and the follicle starts to shrink. The last phase is where the eyelash rests, and it is called the Telogen phase. The eyelash stays in this phase for about a hundred days till it falls out naturally.
There are ninety to one hundred and fifty eyelashes on the upper eyelid, while the lower eyelid has a lesser amount, ranging from seventy to eighty eyelashes. An embryo develops it eyelashes from the seventh to eighth week inside the womb. If the eyelash is pulled out or falls off, it will take as long as seven to eight weeks to grow back.
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