The Collaborative International Dictionary
juvenile hormone \juvenile hormone\ (Zo/'94l.) n. A hormone secreted by insects which inhibits the molting of an insect from its juvenile into its adult form; also, substances having similar activity, but produced by plants.
Wiktionary
n. Any of a group of sesquiterpene hormones that regulate insect physiology by preventing molting of the exoskeleton and thus development of the larva
Wikipedia
Juvenile hormones (JHs) are a group of acyclic sesquiterpenoids that regulate many aspects of insect physiology. JHs regulate development, reproduction, diapause, and polyphenisms.
In insects, JH (formerly called neotenin) refers to a group of hormones, which ensure growth of the larva, while preventing metamorphosis. Because of their rigid exoskeleton, insects grow in their development by successively shedding their exoskeleton (a process known as molting).
Juvenile hormones are secreted by a pair of endocrine glands behind the brain called the corpora allata. JHs are also important for the production of eggs in female insects.
JH was discovered in 1965 and the first molecular structure of a final six was solved in 1967.
Most insect species contain only juvenile hormone (JH) III. To date JH 0, JH I, and JH II have been identified only in the Lepidoptera (butterflies and moths). The form JHB (JH III bisepoxide) appears to be the most important JH in the Diptera, or flies. Certain species of crustaceans have been shown to produce and secrete methyl farnesoate, which is juvenile hormone III lacking the epoxide group. Methyl farnesoate is believed to play a role similar to that of JH in crustaceans.
Being a sesquiterpenoid, JH chemical structure differs significantly from the structure of other animal hormones. Some JH analogs have been found in conifers.
Usage examples of "juvenile hormone".
One is tempted to think that the thymus might produce some secretion which, like the juvenile hormone of insects, keeps a child from maturing.
For instance, a juvenile hormone for fleas, methoprene, has been isolated and is now being used successfully to keep these insects from ever attaining their fertile maturity.
Dropping human juvenile hormone on Russia would cause early maturation.
It was quite a showplace and Harriman suspected that Robertson used juvenile hormone to control insect life without regard to environmental formulas.