Corpus Allatum and Prothoracic Gland
The corpus allatum is situated in the neck region of insects. It is generally a rounded, solid and translucent structure. Nerves to corpus cardiacum in front connect it. The allatum is densely packed along with small nuclei with little cytoplasm around them. It produces juvenile hormone. The juvenile hormone is a straight chain terpenoid (a type of lipid) compound of 16 to 19 carbon atoms.
Figure: Prothoracic glands of an insect
The prothoracic glands are generally made up of loose strings of cells situated in the prothorax of immature insects. They generate the steroid hormone ecdysone. These glands undergo degeneration in the adult.