Tufts OpenCourseware
PREV : Digital pad of the dog.
Author: Paul Kwan, Ph.D.
Sinus hair follicle from a dog.
Description:Sinus or tactile hair follicle is specialized for tactile sense. Each is a single follicle which is much larger than regular hair follicle and is characterized by a blood filled sinus between the outer and the inner layers of the dermal sheath. The extrnal dermal sheath is quite thick and eosinophilic, and is shaped like a 'bracket'. The two dark, purplish vertical lines represent the external root sheath. Only a portion of the hair is seen in this section along with a glancing section of the bulb. The upper portion of the sinus (annular sinus) is a simple cavity filled with blood and does not contain connective tissue. The lower portion of the sinus (trabecular sinus) contains trabeculae formed by fibroelastic tissue. Numerous nerves (not discernable here) penetrate the external dermal sheath and ramify in the trabeculae and inner dermal sheath. Vibrations picked up by the hair is magnified by the blood filled sinus and transduced by the nerves. Original mag. 100x H&E Sinus hair. Skin appendages. Integument System. Dog.