Columns of epidermal cells project into the skin initially to form an invagination called the feather follicle. Continued growth results in their projection out of the skin to form the feather shaft. These columns then separate from each other, become keratinized and develop into barbs. Feather growth is initiated by mesodermal papillae which die in the grown feather to form feather pulp. Examine the dried specimens.
Dermal papillae die to form the core substance of hair follicles.
Note the similarities between hair and feathers both in development and in general anatomy. They both possess dermal papillae, shafts, an inner pulp and columns of specialised keratinized cells. Examine the hair on the vertebrate groups on demonstration. In many cases they retain a connection to the stratum corneum whereby their secretions can be released at the skin surface. Draw and label slides of the snake, frog and human scalp.