Follicle

Follicle

A follicle is a small sac or cavity in the body that contains a substance. In the context of human biology, follicles are often associated with the hair and skin, as well as the ovaries and thyroid gland.

Hair and Skin Follicles

Hair follicles are part of the skin's integumentary system. They produce hair by packing old cells together. Attached to the follicle is a tiny bundle of muscle fiber called the arrector pili, which is responsible for causing the hair to stand up when the body is cold.

Skin follicles, also known as sebaceous glands, are small sacs that produce and secrete sebum, a fatty substance that helps to keep the skin and hair moisturized.

Ovarian Follicles

In the ovaries, follicles are the basic units of female reproductive biology. Each one contains an immature egg, or oocyte, and is responsible for the maturation and release of the egg during the menstrual cycle.

Thyroid Follicles

The thyroid gland contains numerous follicles that produce and store thyroid hormones, which regulate the body's metabolism.

See Also

• Hair
• Skin
• Ovaries
• Thyroid gland

References

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