endogenous
adjective
en·dog·e·nous en-ˈdä-jə-nəs 
1
: growing or produced by growth from deep tissue
endogenous plant roots
2
a
: caused by factors inside the organism or system
suffered from endogenous depression
endogenous business cycles
b
: produced or synthesized within the organism or system
an endogenous hormone
endogenously adverb
Did you know?
When biologists need to make a distinction between things that are produced within a cell or organ and things that affect it from the outside, they use the terms endogenous and exogenous. It used to be thought, for instance, that mutations in cells always resulted from exogenous causes, until it was discovered that substances in the body, including those called oxidants, could cause them endogenously as well. "Circadian rhythms"—the regular cycles, roughly 24 hours in length, that plants, animals, and humans rely on to regulate their days—are endogenously generated and don't actually depend on the sun for their timing.
Example Sentences
Recent Examples on the Web Inside, the fluid that is circulating is actually a one-to-one mixture of the animal’s endogenous blood and our perfusate. 
Tanya Lewis, Scientific American, 10 Aug. 2022 The line was also free of a specific virus that inserts itself into the pig genome (porcine endogenous retrovirus C, or PERV-C) and was raised in conditions that should limit pathogen exposure. John Timmer, Ars Technica, 24 June 2022 According to some estimates, nearly 10 percent of our own DNA comes from endogenous retroviruses, ancient viruses that infected humans millions of years ago and have been passed down since then. Joseph Osmundson, The Atlantic, 8 June 2022 But the research concerning endogenous testosterone, the kind that the body makes naturally, was less settled. Louisa Thomas, The New Yorker, 17 Mar. 2022 This stability seems endogenous rather than a mere reflection of federal aid. Andrew Stuttaford, National Review, 21 Nov. 2021 EVs are natural vesicles secreted by endogenous cells to protect and transport small RNAs across cells and biological barriers and therefore should be biocompatible with the host’s immune system. Chao Yan, Scientific American, 17 June 2020 Now, thanks to the work of Dr. George Church and his colleagues from Harvard Medical School, scientists can snip all 62 genes responsible for producing pig endogenous retroviruses. William A. Haseltine, Forbes, 1 Nov. 2021 Focusing on human endogenous retroviruses, or HERVs, Thakkar’s video explains how viruses are made from genes and a protein shell that need to replicate and create retroviruses in the human body. Allana Haynes, baltimoresun.com, 13 Oct. 2021 See More
Tanya Lewis, Scientific American, 10 Aug. 2022 The line was also free of a specific virus that inserts itself into the pig genome (porcine endogenous retrovirus C, or PERV-C) and was raised in conditions that should limit pathogen exposure. John Timmer, Ars Technica, 24 June 2022 According to some estimates, nearly 10 percent of our own DNA comes from endogenous retroviruses, ancient viruses that infected humans millions of years ago and have been passed down since then. Joseph Osmundson, The Atlantic, 8 June 2022 But the research concerning endogenous testosterone, the kind that the body makes naturally, was less settled. Louisa Thomas, The New Yorker, 17 Mar. 2022 This stability seems endogenous rather than a mere reflection of federal aid. Andrew Stuttaford, National Review, 21 Nov. 2021 EVs are natural vesicles secreted by endogenous cells to protect and transport small RNAs across cells and biological barriers and therefore should be biocompatible with the host’s immune system. Chao Yan, Scientific American, 17 June 2020 Now, thanks to the work of Dr. George Church and his colleagues from Harvard Medical School, scientists can snip all 62 genes responsible for producing pig endogenous retroviruses. William A. Haseltine, Forbes, 1 Nov. 2021 Focusing on human endogenous retroviruses, or HERVs, Thakkar’s video explains how viruses are made from genes and a protein shell that need to replicate and create retroviruses in the human body. Allana Haynes, baltimoresun.com, 13 Oct. 2021 See More Word History
First Known Use
1830, in the meaning defined at sense 1
Medical Definition
endogenous
adjective
en·dog·e·nous en-ˈdäj-ə-nəs
variants also endogenic
ˌen-də-ˈjen-ik
1
: growing from or on the inside
endogenous spores
2
: caused by factors within the body or mind or arising from internal structural or functional causes
endogenous malnutrition
endogenous psychic depression
3
: relating to or produced by metabolic synthesis in the body
endogenous opioids
endogenous amino acids
compare exogenous