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Immune System Development: Encyclopedia of Children's Health |
 | | The child's immune system is an intricate network of interdependent cell types, substances, and organs that collectively protect the body from bacterial, parasitic, fungal, viral infections, and tumor cells. |
 | | The immune system was not recognized as a functional unit of the body until the late twentieth century, probably because its parts are not directly connected to each other and are spread in different parts of the body. |
 | | Immune system—The system of specialized organs, lymph nodes, and blood cells throughout the body that work together to defend the body against foreign invaders (bacteria, viruses, fungi, etc.). |
| health.enotes.com /childrens-health-encyclopedia/immune-system-development (1704 words) |
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