The term "IG tract" is not a standard medical or scientific term. It's possible there's a misunderstanding or a typo.

To help me understand what you're looking for, could you please provide more context?

For example:

* Where did you encounter the term "IG tract"? (e.g., a medical article, a website, a conversation)

* What is the overall topic or subject being discussed?

* Can you provide any other related terms or information?

Once I have more information, I can help you identify what you are looking for.