Please review my paragraph

Topic: In about 140 words, write a paragraph about the advantages of animals testing/ experiments on animals

My paragraph:

In recent years, the animals testing not only becomes more and more essential to the medical researches but have a number of advantages as well . First and foremost, there is not any research alternative available since animals are the closest to humans on the Earth. With similar anatomical structure such as endocrine system, central nervous system, and immune system, the experts can predict the reactions of humans to illness. Second, most of the medical advancements stem from animals testing. Experts can get more information about new drugs or viruses by observing the effect on subjects thereby minimize the side effects or potential harm. Third, animals experiments contribute to a number of new treatments and cures for hazardous diseases. For instance, Insulin was discovered after an experiment was conducted on a dog’s pancreas. That means people having diabetes would die every year without that tests. Four, it is illegal to use humans as testing subjects in such risky experiments which can result in death. Additionally, the risk percent would be incredibly high without those experiments, consequently using animals is the best choice. Finally, when a vaccine is produced, it is subjected to a series of tests and trials before being approved for medical usage on people. In conclusion, animals testing is indispensable to the world’s medicine.