Editing Cell growth (section)

== Measurement methods ==
The cell growth can be detected by a variety of methods.
The cell size growth can be visualized by [[microscopy]], using suitable stains. But the increase of cells number is usually more significant. It can be measured by manual counting of cells under microscopy observation, using the dye exclusion method (i.e. [[trypan blue]]) to count only viable cells. Less fastidious, scalable, methods include the use of [[cytometer]]s, while [[flow cytometry]] allows combining cell counts ('events') with other specific parameters: fluorescent probes for membranes, cytoplasm or nuclei allow distinguishing dead/viable cells, cell types, cell differentiation, expression of a [[biomarker]] such as [[Ki-67 (protein)|Ki67]]. The total mass of a cell, which comprises the mass of all its components including its water content, is a dynamic magnitude and it can be measured in real-time and tracked over hours or even days using an inertial picobalance.<ref>{{Cite journal |last1=Martínez-Martín |first1=David |last2=Fläschner |first2=Gotthold |last3=Gaub |first3=Benjamin |last4=Martin |first4=Sascha |last5=Newton |first5=Richard |last6=Beerli |first6=Corina |last7=Mercer |first7=Jason |last8=Gerber |first8=Christoph |last9=Müller |first9=Daniel J. |date=October 2017 |title=Inertial picobalance reveals fast mass fluctuations in mammalian cells |url=https://www.nature.com/articles/nature24288 |journal=Nature |language=en |volume=550 |issue=7677 |pages=500–505 |doi=10.1038/nature24288 |pmid=29072271 |bibcode=2017Natur.550..500M |issn=1476-4687}}</ref><ref>{{Cite journal |last1=Cuny |first1=Andreas P. |last2=Tanuj Sapra |first2=K. |last3=Martinez-Martin |first3=David |last4=Fläschner |first4=Gotthold |last5=Adams |first5=Jonathan D. |last6=Martin |first6=Sascha |last7=Gerber |first7=Christoph |last8=Rudolf |first8=Fabian |last9=Müller |first9=Daniel J. |date=2022-06-22 |title=High-resolution mass measurements of single budding yeast reveal linear growth segments |journal=Nature Communications |language=en |volume=13 |issue=1 |pages=3483 |doi=10.1038/s41467-022-30781-y |issn=2041-1723 |pmc=9217925 |pmid=35732645|bibcode=2022NatCo..13.3483C }}</ref> A cell's buoyant mass, which corresponds to the total mass of the cell minus that of the fluid it displaces, can be measured using suspended microchannel resonators.<ref>{{Cite journal |last1=Burg |first1=Thomas P. |last2=Godin |first2=Michel |last3=Knudsen |first3=Scott M. |last4=Shen |first4=Wenjiang |last5=Carlson |first5=Greg |last6=Foster |first6=John S. |last7=Babcock |first7=Ken |last8=Manalis |first8=Scott R. |date=April 2007 |title=Weighing of biomolecules, single cells and single nanoparticles in fluid |url=https://www.nature.com/articles/nature05741 |journal=Nature |language=en |volume=446 |issue=7139 |pages=1066–1069 |doi=10.1038/nature05741 |pmid=17460669 |bibcode=2007Natur.446.1066B |hdl=11858/00-001M-0000-0014-9C58-F |issn=1476-4687|hdl-access=free }}</ref>

Beside the increasing number of cells, one can be assessed regarding the metabolic activity growth, that is, the [[Carboxyfluorescein diacetate|CFDA]] and [[calcein]]-AM measure (fluorimetrically) not only the membrane functionality (dye retention), but also the functionality of cytoplasmic enzymes (esterases). The [[MTT assay]]s (colorimetric) and the [[resazurin]] assay (fluorimetric) dose the mitochondrial redox potential.

All these assays may correlate well, or not, depending on cell growth conditions and desired aspects (activity, proliferation). The task is even more complicated with populations of different cells, furthermore when combining cell growth interferences or [[toxicity]].