How many cells are in the human body: a new study has provided an answer
Scientists analyzed more than 1,500 studies and 400 cell types in 60 tissues. As a result, they were able to identify the total number of cells in the human body.According to a new analysis of more than 1,500 papers, the average adult male has about 36 trillion cells, adult women have 28 trillion, and 10-year-old children have about 17 trillion. One trillion is 10 to the 12th degree, or one million million million.
To find out, the authors of a new study published in the journal PNAS looked at the size and number of 400 cell types in 60 body tissues, including muscle, nerve and immune cells.
Although scientists have previously estimated a similar number of cells - between 30 trillion and 37 trillion - in adult male males, the authors said, no one had yet studied the relationship between the size and number of cells throughout the body.
It turns out there is a "trade-off" between cell size and cell number: the larger the cell, the smaller their total number compared to smaller cells. This means that if cells are clustered by size, each cluster contributes equally to total body weight.
The authors recognized several limitations of the study. For example, they focused on the bodies of "average" adults and children. According to the International Commission on Radiological Protection reference data, a standard adult male weighs 70 kg, an adult female weighs 60 kg, and a child weighs 32 kg. This, in particular, does not reflect the huge differences in size and weight that exist between people. In addition, scientists have often had to rely on conclusions about cell size drawn from microscopy and other indirect measurements, rather than direct measurements of the mass of different cell types.