Pin feather

[2][3][4][5] As the pin feather grows longer, the blood supply is concentrated in only the base of the shaft, and the tip of the shaft encases the feather itself in a waxy coating.

As moulting birds preen, they remove the waxy coating, and the feather unfurls.

At the base of the feather follicle, epithelial cells proliferate to grow the epidermal collar or cylinder.

As the epidermal cylinder extends through dermis, it differentiates into a protective peripheral sheath, longitudinal barb ridges, and growth plates.

Pin feathers are sensitive, and some pet birds do not enjoy being handled while moulting for this reason.