Contact with stomach acid keeps the mucin lining the epithelial cell layer in a spongy gel-like state. This consistency is impermeable to the bacterium Heliobacter pylori. However, the bacterium releases urease which neutralizes the stomach acid. This causes the mucin to liquefy, and the bacterium can swim right through it.

Full story at:
http://www.nsf.gov/news/news_summ.jsp?cntn_id=115409

Praise:
“Thanks, Zina! I'm really a fan of finding clear ways to communicate science, and this illustration is a great example. Thank you for your excellent work.”

--Randy H. Ewoldt
Mechanical Engineering Department
Massachusetts Institute of Technology

Also featured in:
MedicineWorld.org
http://medicineworld.org/stories/lead/8-2009/uncovering-the-secrets-of-ulcer-causing-bacteria.html

Science Daily
http://www.sciencedaily.com/releases/2009/08/090812163805.htm