part of part of paneth cell paneth cell of epithelium of small intestine FMA:263104 A paneth cell that is part of the epithelium of small intestine. https://cellxgene.cziscience.com/cellguide/CL_1000343 Paneth cells of the epithelium of the small intestine, often referred to simply as Paneth cells, are a type of specialized secretory cell that forms an integral part of the intestinal crypts of Lieberkühn – gland-like invaginations lining the small intestine. Named after the Austrian physician Josef Paneth, who first identified them in the late 19th century, these cells are significant because of their substantial involvement in the mucosal immune system and intestinal stem cell maintenance. Functionally, Paneth cells play a key role in maintaining gut homeostasis and in the first line of antimicrobial defense, mainly through the secretion of a range of antimicrobial peptides and proteins. These include lysozymes, cryptdins, or alpha-defensins, which have potent activity against various gut pathogens including bacteria, fungi, and parasites. Furthermore, Paneth cells of the small intestine are also known to release secretory phospholipase A2, an enzyme active against gram-positive bacteria. Additionally, they secrete several growth factors like EGF, TGF-alpha, and Wnt3, which are crucial for stem cell support and the overall maintenance of intestinal mucosal integrity. The unique location of Paneth cells at the base of the crypts positions them in very close proximity to intestinal stem cells. This not only facilitates their role in stem cell maintenance but also involves them in epithelial regeneration and repair following injury. Dysfunctional Paneth cells have been associated with several gut disorders, like Crohn’s disease and necrotizing enterocolitis. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.) small intestine secretory cell epithelium of small intestine