Endogeny, in biology, refers to the property of originating or developing from within anorganism,tissue, orcell.[1]
For example,endogenous substances, andendogenous processes are those that originate within a living system (e.g. anorganism or acell). For instance,estradiol is an endogenousestrogenhormone produced within the body, whereasethinylestradiol is an exogenous synthetic estrogen, commonly used inbirth control pills.
In contrast,exogenous substances andexogenousprocesses are those that originate from outside of an organism.
The dictionary definition ofendogeny at Wiktionary