Hierachy
![Immune System](https://medlineplus.gov/images/immunesystem.png)
Immune System
![Thymus](https://i.ytimg.com/vi/NtGWhj_s15A/maxresdefault.jpg)
Thymus
Epithelial tissues
columnar cells
cuboidal cells
![squamous cells](http://library.med.utah.edu/WebPath/jpeg1/NEO095.jpg)
squamous cells
Lymphatic Tissues
lymphocytes
macrophage cells
reticular cells
Bone Marrow
Stromal
Stromal cells
Mesenchymal stem cells
hemopoietic
Hematopoietic stem cell
White blood cell
Spleen
White pulp
T cell
Red pulp
Red Blood Cells
Plasma
granulocytes
Tonsils
Lymphatic Tissues
lymphocytes
![macrophage cells](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Macrophage.svg/2000px-Macrophage.svg.png)
macrophage cells
reticular cells
![Lymph Nodes](http://images.medicinenet.com/images/image_collection/anatomy/surface-lymphatics.jpg)
Lymph Nodes
Lymphatic Tissues
lymphocytes
macrophage cells
reticular cells
Dense connective tissue
![Fibroblast cells](https://micro.magnet.fsu.edu/primer/techniques/fluorescence/gallery/cells/3t3/images/3t3cellslarge1.jpg)
Fibroblast cells
Collagen fibers
Elastin fibers
![Lymphatic System](https://s-media-cache-ak0.pinimg.com/736x/4a/02/ba/4a02ba4b0c1fcff0b0c74dcce3734863.jpg)
Lymphatic System
Tonsils
Lymphatic Tissues
lymphocytes
macrophage cells
reticular cells
![Spleen](http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/articles/image_article_collections/anatomy_pages/Spleen2.jpg?resize=646px:*&output-quality=100)
Spleen
White pulp
T Cells
Red pulp
Red Blood Cells
Plasma
granulocytes
Thymus
Lymphatic Tissues
lymphocytes
macrophage cells
reticular cells
Epithelial tissues
columnar cells
cuboidal cells
squamous cells
Appendix
Lymphatic Tissues
lymphocytes
macrophage cells
reticular cells
Lymph Nodes
Lymphatic Tissues
lymphocytes
macrophage cells
reticular cells
Dense connective tissue
Fibroblast cells
Collagen fibers
Elastin fibers
Bone Marrow
hemopoietic
Hematopoietic stem cell
White blood cell
stromal
Stromal cells
![Mesenchymal stem cells](https://www.sciencellonline.com/media/catalog/product/cache/1/image/a6f8fb4f61eb724cff40f184d1fbcab0/7/5/7500_3.jpg)
Mesenchymal stem cells
![Musculoskeletal system](http://tylersmusculoskeletalsystem.weebly.com/uploads/1/7/2/8/17289344/465421_orig.jpg)
Musculoskeletal system
![Bones](http://www.organsofthebody.com/images/bones.jpg)
Bones
Bone Tissue
osteoblasts
![osteoclasts](http://www.hybridmedicalanimation.com/wp-content/uploads/2010/07/osteoclasts-sourcebook11.jpg)
osteoclasts
osteocytes
osteoprogenitor
Connective tissue
Fibroblast
![Mast cells](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a0/SMCpolyhydroxysmall.jpg/250px-SMCpolyhydroxysmall.jpg)
Mast cells
Plasma cells
Bone Marrow
hemopoietic
Hematopoietic stem cell
White blood cell
stromal
Stromal cells
Mesenchymal stem cells
Muscles
Skeletal muscle tissue
Skeletal muscle cells
Smooth muscle tissue
Smooth Muscle Cells
Cardiac muscle tissue
Cardiac Muscle Cells
The immune system is made up of a network of cells, tissues, and organs that work together to protect the body against infection and maintain overall health.
Vaccines work by stimulating the immune system to produce antibodies against a foreign invader without actually infecting the individual with the disease.
![](https://i.ytimg.com/vi/zQGOcOUBi6s/maxresdefault.jpg)