Akademik

folliculus pili

[TA] hair follicle: one of the tubular invaginations of the epidermis that enclose the hairs, and from which they grow. It is divided into upper and lower segments: the upper comprises the follicular infundibulum (extending from the free surface to the sebaceous gland) and the isthmus (extending from the sebaceous gland to the arrector pili muscle); the lower comprises the hair bulb and the part sometimes referred to as the stem. In the lower part, the hair cuticle is surrounded by the inner and outer root sheaths, enclosed within a dermal sheath.

Folliculus pili (hair follicle). (A), Longitudinal section, comprising the infundibulum, isthmus, stem, and bulb; (B), transverse section of follicle, showing the hair shaft and surrounding follicular sheaths.

Medical dictionary. 2011.