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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Mucin is not secreted by
assistant
The correct answer is  Paneth cells are a specific type of cell within the crypts of Lieberkuhn.
These cells have atypically oriented bright eosinophilic granules containing a variety of antimicrobial proteins and play a role in mucosal immunity (and not mucin secretion)

Brunner's glands: are sub-mucosal mucus gland within the duodenum.
Goblet cells: are mucin-secreting cells.
Crypts of Lieberkuhn: are lined by goblet cells besides other cell types.

These are thus also involved in mucin secretion.