Histological study on the retrocerebral-endocrine complex with special reference to neurohaemal involvement of aorta and pericardial cells in Coccinella septempunctata (L.) (Coccinellidae-Coleoptera).
About nine median neurosecretory cells (NSC) are situated in the antero-dorsal position on either side of the pars intercerebralis of the brain. No lateral NSC could be detected. The axonic bundles, after their decussation, emerge out of the brain in the form of a single nervi corporis cardiaci (NCC) on either side. These soon undergo a dichotomy--one set of nerve fibers enter the lobulated corpus cardiacum (CC) and the other set ramify over the surface of the aorta and sends out distinct branches to the individual large, oval-shaped, pericardial cells all along the length of the aorta. Presence of neurosecretory material (NSM) could be demonstrated both in aortal wall as well as along the nerve branches that innervate the pericardial cells. Traces of NSM could be detected within the cytoplasm of the pericardial cells. While the involvement of aorta and pericardial cells, as an additional neurohaemal organs was well documented for several species of Hemiptera, the present report for Coleoptera seems to be new and of considerable interest. Thus it would seem that the role of the aorta and pericardial cells as accessory neurohaemal organ is perhaps of wider occurrence than was hitherto believed. The irregularly lobulated CC contains copious amounts of thick clumps of NSM which, by and large, tends to show a peripheral distribution. Few intrinsic secretory cells are noticeable. The CC, at its postero-lateral border forms a cap- or hood-like projection that partially overlaps the corpus allatum (CA) below. At the mesial border, the CC sends out a lobe which seems to fuse with the aortal wall. The shape of CA shows individual variation. In some, it is oval while in others it is spherical, but always with a well defined outline. No allatal nerve is demonstrable. Instead, the CA is broadly connected with the hood region of the CC. AF-positive material is also detectable in the CA, which also tends to be peripherilly distributed.
D000818:Animals; D001011:Aorta / Q000648:ultrastructure; D001921:Brain / Q000502:physiology; D001517:Coleoptera / Q000166:cytology*; D003335:Corpora Allata / Q000648:ultrastructure; D005260:Female; D009490:Neurosecretory Systems / Q000166:cytology*