A 30-year-old woman comes to your office for a dental examination. She has not been to the dentist in 2 years. The patient has type I diabetes, which requires her to take insulin. She is otherwise in good health. On intraoral examination, you notice that the dorsum of her tongue has a thick, matted appearance and diagnose her with hairy tongue. Which type of papillae is affected that causes the hairlike appearance of her tongue?