Feather formation

Origin and development of a feather from the feather papilla in the dermis; in a young feather the dermal papilla penetrates deeply into the quill and is covered by many layers of cells of the germinative part of the epidermis, which by division and keratinization give rise to the feather; at that time the quill is red to dark blue and is termed “pisk”. During feather development and keratinization, the quill and keratinized cells become filled with air and the feather papilla retracts back into the dermis.