Ear hair canal is sometimes trimmed for cosmetic reasons. Excessive hair growth within or on the ear is known medically as "auricular hypertrichosis". Some men, particularly in the male population of India, have coarse hair growth along the lower portion of the helix, a condition referred to as "having "hairy pinnae"" ("hypertrichosis lanuginosa acquisita"). Hair is a protein filament that grows from follicles in the dermis, or skin. With the exception of areas of glabrous skin, the human body is covered in follicles which produce thick terminal and fine vellus hair. It is an important biomaterial primarily composed of protein, notably keratin.
Bone morphogenetic protein 4 hair is through restricting growth factor expression in the hair matrix and antagonism between growth and differentiation signaling. Pathways that regulate hair follicle formation and hair growth are key in developing therapeutic methods for hair loss conditions. Such conditions include the development of new follicles, changing the shape of characteristics of existing follicles, and the altering of hair growth in existing hair follicles. Furthermore, BMP4 and the pathway through which it works may provide therapeutic targets for the prevention of hair loss. Bone morphogenetic protein 4 Bone morphogenetic protein 4 is a protein that in humans is encoded by "BMP4"