Do You Approve Animal Experiments?

Hello eveyone! I just browsed a group of pictures about animal experiments. They are impressive and "breath-taking". It is hard to simply approve or reject these experiments. After all, most of these experiments are devoted to we humans. Here I list some reasons for approving or rejecting such animal experiments.
Approval:
1) We study a new kind of medicine. We don't how it works. Ofcourse we can't test them on humans. We have to refer to some animals close to humans biologically.
2) We want to understand how an organ works. For example, we want to know how the brain acts or reacts. We can not open a human's head and do experiement with his/her brain. We have to use the animals.
3) We want to erase some dangerous things. For example, there are some explosive things somewhere in some room. We have to find them out. But we don't know where they are. If we are not careful enough, they would explode and kill us. In this situation, we may use dogs or other trained animals to find the explosives.

No matter how many good reasons for approving animal experiments I list, most of the results are that animals won't have a good ending. They are propabably very ill,  very ugly or even die at once. Most of people have the natural compassion. Some of us can't go over such cruel things. Here I give some reasons for rejecting such experiments.
Rejection:
1) Animals suffer great pain. It is unavoidable that they have to suffer much pain when being tested.
2) Animals live unfreely. Before being tested, most of animals are confined to a limited room. They are born to be tested and they die of being tested. They don't have a comfortable home.
3) Animals would die in most cases. If most of the experiments would NOT cause the animals to die, I would feel better. But in most cases, lots of failures bring death to lots of animals.

Although I list many reasons for approving or rejecting animal experiments, it is still an open question. It is a fact that the relation of animals and humans is much closer. I want to hear your voice!