List of distinct cell types in the adult human body
From Wikipedia, the free encyclopedia
The adult human body is estimated to contain about 30 trillion (3×1013) human cells, with the number varying between 20 to 40 trillion depending on factors such as sex, age, and weight. Additionally, there are approximately an equal number of bacterial cells. The exact count has not yet been empirically measured in its entirety and is based on smaller samples of empirical observation.[1][2][3][4][5][6]
Human cells have been categorized into over 500 cell types based on their location and function within the body.[2] There is usually a significant variation in these cell types depending on the specific surface proteins they possess. Approximately 1,000 cells have been assigned unique names, most of which are documented in the HubMap database.
Cell type | % cell count | |
Erythrocytes (red blood cells) | 84.0 | |
Platelets | 4.9 | |
Bone marrow cells | 2.5 | |
Vascular endothelial cells | 2.1 | |
Lymphocytes | 1.5 | |
Hepatocytes | 0.8 | |
Neurons and glia | 0.6 | |
Bronchial endothelial cells | 0.5 | |
Epidermal cells | 0.5 | |
Respiratory interstitial cells | 0.5 | |
Adipocytes (fat cells) | 0.2 | |
Dermal fibroblasts | 0.1 | |
Muscle cells | 0.001 | |
Other cells | 2.0 |
In 1996, scientists revealed a 'map' of 16000 human genes.[7] This lead to estimates that humans likely had around 100 000 genes[8] (or regions that code for human proteins). However, actual sequencing did not start before around 1999, and it was not until 2003[9] that the first complete draft of a human genome revealed that there was roughly 20000-25000, as most DNA does not code for any protein but rather serve other more administrative functions or leftovers from the past. It is difficult to say that there have not been similar mistakes when estimating how many cells humans have as there are still substantial gaps in understanding human cells.[citation needed]