Chullin 49 - A Needle Found in the Liver
There was once a case of a needle found in the liver of an animal, and Mar the son of Rav Yosef was inclined to rule the animal terefah. Rav Ashi said to him, "Why is this worse than a needle in an ordinary piece of meat? Rather, I look at the position of the needle. If its head it sticking out of the liver, then clearly it has come into the liver by way of puncturing from the outside, and thus has made an animal a terefah, because it punctured the digestive track. But if the head is inside, then it must have taken the vascular route and is beginning to exit out of the liver, thus the animal is kosher."
Abomasum is the fourth and final division in the stomach of a cow. If it was punctured, the animal is terefah. Incidentally, the kohanim, who receive this abomasum with its rennet as one of the gifts due them, have adopted the practice of allowing this fat for consumption, following Rabbi Ishmael, who is also a kohen. He also explains the order of blessings to their benefit, as: they bless the people, and God blesses them.
Art: Jules (Adolphe Aime Louis) Breton - Peasant Woman Threading A Needle