Corpus Cardiacum - Endocrine Organs
We before mentioned that corpus cardiacum (pl. corpora cardiaca) is a neurohemal organ in insects. It is gland of neural origin. They are considered as transformed ganglia. Except for these, we will discuss in the ensuing section a number of other endocrine glands. Most of them are, though, of epithelial origin. The corpora cardiaca are situated close behind the brain dorsally, on either side of the dorsal aorta or stay in close association with it. They appear as a white bluish organ in dissections and thus we can easily locate them under dissection microscope. Though they are neurohemal organs in insects like they contain fibre terminations of NSCs situated in the pars inter-cerebralis of the brain, they comprise their own cells too. That is, they contain intrinsic cells, which synthesise hormones different from the ones produced by the NSCs of the pars inter-cerebralis. Thus they have a dual function. They are the neruohaemal organs as well as endocrine glands in their own right. They receive generally two or sometimes three nerves from the brain in front and are connected to the corpora allata (sl. corpus allatum) behind, by allatal nerves. In a number of insects there may be also ordinary non-secretory neurones in the corpora cardiaca.