SKIN 04A

Here, at higher magnification, is the lower of the two hair follicles labelled "5" in SKIN 04. Hair follicles are very complex structures, their appearance varying on the orientation and location (relative to the base of the hair follicle) of the plane of section, as well as the activity state of the follicle. This follicle has been sectioned somewhat obliquely, near its base (note the surrounding fat cells). In the center of the follicle is the actual hair shaft, whose cortex ("2") is somwhat more heavily pigmented than its medulla ("1"). Immediately around the hair shaft is the cuticle ("3"). Next comes the inner root sheath ("4") which, because it has multiple cellular layers, takes on several different appearances depending on the plane of section. Outside is the outer root sheath (spanned by the bar labelled "5") which most clearly resembles the epidermis, from which in fact all of the hair follicle components arise. The thin line labelled "6" is the basement membrane of the outer root sheath (continuous with the basement membrane of the epidermis) and "7" is connective tissue, sometimes referred to as the adventitial dermis.

Slide M-4, field O38 of finder slide B, 16X objective