ENDOCRINE GLANDS OF AN INSECT -
The endocrine glands of cockroach are as follows.
1. Intercerebral gland cells. These cells lie in the brain. They secrete brain hormone which activates the protho- racic glands to secrete their hormone.
2. Corpora Cardiaca. These are a pair of elongated structures situated on either side of the oesophagus behind the brain. They secrete a growth hormone which increases heart rate, peristalsis of hind gut but decreases the peristalsis of the foregut. It also regulates protein metabolism.
3. Corpora Allata. These are a pair of srnaIl rounded bodies lying just behind the corpora cardiaca. They secrete a juvenile hormone or neotenine hormone in the nymph. This hormone retains the nymphal characters and checks the appearance of the adult characters. When the juvenile hormone is absent, it permits the appearance of the adult characters. In adult the corpora allata again become active and secrete gonadotropic hormone.
4. Prothoracic glands. These are fairly large, irregular in shape and situated in the prothorax. They secrete a hormone caIled ecdyson (steroid hormone) which controls last exuviae or moulting of the nymph. These glands degenerate after metamorphosis.