PANETH cells are rich in: (AIPG 2009)
|C||Option A,B is right|
Paneth cells—endocrine cells located in the depths of the crypts of Lieberkuhn—secrete defensins, naturally occurring peptide antibiotics that are also secreted elsewhere in the body .
I. Defensins: The principal defense molecules secreted by Paneth cells are alpha-defensins, also known as cryptones. These peptides have hydrophobic and positively-charged domains that can interact with phospholipids in cell membranes. This structure allows defensins to insert into membranes, where they interact with one another to form pores that disrupt membrane function, leading to cell lysis. Due to the higher concentration of negatively-charged phospholipids in bacterial than vertebrate cell membranes, defensins preferentially bind to and disrupt bacterial cells, sparing the cells they are functioning to protect. Paneth cells are stimulated to secrete defensins when exposed to bacteria (both Gram positive and negative types) or such bacterial products as lipopolysaccharide, muramyl dipeptide and lipid A.
II. Other secretions: In addition to defensins, Paneth cells secrete lysozyme, zinc and phospholipase A2, which have clear antimicrobial activity. This battery of secretory molecules gives Paneth cells a potent arsenal against a broad spectrum of agents, including bacteria, fungi and even some enveloped viruses.
III. Paneth cells secrete a number lysozymes into the lumen of the crypt, thereby contributing to maintenance of the gastrointestinal barrier.