LIGHT AND SCANNING ELECTRON-MICROSCOPIC STUDIES ON THE CEREBRAL NEUROSECRETORY-SYSTEM IN INDIAN OCTOCHAETID EARTHWORM, EUTYPHOEUS-GAMMIEI (BEDDARD)

The cerebral ganglion of the earthworm, Eutyphoeus gammiei reveals mai nly two types of neurosecretory cells (NSCS) - A and B. Cortical A cel ls stain intensely with AF and are differentiated into A(1), A(2) and A(3) subtypes. The subcortical B cells, lying close to the neuropile s tain lightly with AF. The axon terminals from the A(2) cells and B cel ls form 'accumulation zone' rich in neurosecretory material (NSM) at t he margin of neuropile. The cerebral ganglion including its outer conn ective tissue sheath (perineurium) in richly vascularised. Compact lay er of visceral muscle cells around the cerebral ganglion assure a bett er mixing up of neurosecretion with blood besides protecting it from m echanical damage.