Cells (細胞 Saibō?) are the basic structural, functional, and biological units of all living organisms. Together they form a multicellular organism, thus they are known as the "building blocks of life". However cells are anthropomorphic in Cells at Work! and have their own stories.

There are roughly 37.2 trillion cells in a human body.

Full-Fledged Cells

Cells Functions Known Characters
Red Blood Cells/Erythrocytes Red blood cells deliver oxygen and nutrients all over the body, as well as carry carbon dioxide away for proper disposal. A young red blood cell is called an erythroblast. AE3803, AA5100, NT4201, DB5963, YO4144, ME0808, AA2153
Platelets/Thrombocytes Platelets close wounds and fix blood clogs. Due to their small size, they are depicted as small children. Platelet
White Blood Cells/Neutrophils Neutrophils are highly mobile white blood cells who are the first to react when pathogenic cells invade the body. They patrol around the body and remove foreign germs and viruses as quickly as possible. U-1146, U-2001, U-2048, U-2626, U-4989, U-1196
Lymphocytes Lymphocytes are a type of white blood cell. They are the bodies most elite white blood cells and serve as the bodies last line of defense when other white blood cells have failed.
  • helper T cells: Act as commanders when a foreign invasion occurs and decides the strategic response for killer T cells to terminate the threats.
  • regulatory T cells: Controls the activity of T cells to prevent them from triggering anomalous immune responses.
  • killer T cells: Kills all pathogenic cells under the command of helper T cells.
  • memory T cells: Killer T cells that encountered the same enemies during a previous foreign invasion, they can mount a faster, stronger immune response than the others as they are "experienced".
  • natural killer cells: Patrols around the body and kills infected cells on sight.
  • B cells: Produces weapons called antibodies to fight against antigens.
  • memory cells: Remembers the immune responses used against antigens and helps prepare white blood cells incase the same antigens invade again.
Helper T Cell, Regulatory T Cell, Killer T Cell, Memory T Cell, Naive T Cell, Natural Killer Cell, B Cell, Memory Cell
Mast Cells/Mastocyte Mast cells release chemicals such as histamines and leukotrienes as a stimulus to excess production of IgE. Mast Cell
Macrophages/Monocytes Macrophages are a type of white blood cell. They terminate stronger bacteria that the Neutrophils are unable to handle and relay information to the lymphocytes. They also clean up the mess in the aftermath of an invasion. Additionally, they assist on raising erythroblasts in the bone marrow. They switch to monocytes when they are roaming in the blood vessels. Macrophage
Eosinophils/Acidophils Eosinophils are a rare type of white blood cell. They defend the body from parasitic invaders, rather than bacterial ones. Eosinophil
Basophils Basophils are the rarest type of white blood cell, making up to less than 1% of the white blood cell population. The role of basophils has not been fully discovered yet. Basophil
Dendritic Cells Dendritic cells oversee the white blood cells communication network; they receive reports from white blood cells in the field and relay the messages to the helper T cells. They are also capable of activating naive T cells, which are T cells that have yet to gain any real combat experience. Dendritic Cell
Intestinal Epithelial Cells Intestinal Epithelial Cells absorbs nutrients and water. They also form a barrier against bacterium in the small intestine.
Goblet Cells Mucous secreting cells that secret the viscous substance mucin. Goblet Cell
M Cells/Microfold Cells M Cells live on the surface of the Peyer's patches. They capture bacteria and viruses and hand them to antigen-presenting cells such as dendritic cells. Microfold Cell
Langerhan Cells Langerhan Cells are a type of dendritic cell of the epidermis. They are responsible on signaling the brain when bacteria and viruses enters the body from the skin. They also protect the skin from ultraviolet rays and dehydration. Langerhan Cell
Hematopoietic Stem Cells Hematopoietic Stem Cells makes blood cells such as red blood cells, white blood cells and platelets. Hematopoietic Stem Cell
Thymic Epithelial Cells Thymic Epithelial Cells nurse lymphocytes and help the differentiation of T cells.
Hair Matrix Cells Hair Matrix Cells create hair through cell division
Sebaceous Gland Cells Sebaceous Gland Cells produce sebum.
Melanocyte Melanocytes produce melanin.
Normal Cells Normal Cells multiply through cell division. The oxygen and nutrients are usually delivered to them. Normal Cell
Cancer Cells Normal Cells that are born mutated due to the copying error in their DNA. They multiply uncontrollably and spread to vital organs, endangering the life of the organism. Cancer Cell

Immature Cells

A Progenitor Cell is a newly born cell that has not differentiate into a specific cell type, similar to a baby.

Lympoid Cell Stem

Cells Possible Growth
B Progenitor Immature B Cell
Immature B Cell/Mature B Cell B Cell
NK/T Progenitor Immature Thymocyte, NK Cell
Immature Thymocyte/Mature Thymocyte Helper T Cell, Killer T Cell

Myeloid Stem Cell Growth

Cells Possible Growth
Myeloblast Myelocyte, Basophil, Eosinophil
Myelocyte/Band Cell Neutrophil
Monoblast Macrophages/Monocyte
Proerythroblast/Erythroblast Red Blood Cell
Promegakaryocyte/Megakaryocyte Platelets
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