The follicles are grouped in feather tracts that are readily visible on the skin of the eviscerated carcass. In the spaces between the tracts, the follicles produce only filoplumes with a rudimentary feather vane at the end of a hair-like shaft. The arrangement of feather follicles is governed by waves of morphogenetic activity that move across the skin of the embryonic chick like ripples on a pond. The large feathers of the wings are called remiges while those of the tail are called retrices . The contour feathers provide the main covering of the body and are interspersed with filoplumes.
Young birds have large numbers of down feathers.
The structure of the vane of a typical feather resembles a hollow quill that has been obliquely sliced and unrolled. Thus, when it is formed within the follicle it is like a hollow cylinder. The lateral branches or barbs of the vane are held together by hooked anterior barbules that catch on the saw-like edges of adjacent posterior barbules. The skin of poultry is dry and does not produce its own oil. In poultry, there is an oil gland located dorsally to the stumpy tail of the bird.