A Light Microscopical Study of the Nervous System of Simocephalus Vetulus Schodler (Cladocera) With Special Reference To Neurosecretion

The neurosecretory system of Simocephalus vetulus Schodler was studied with the light microscope. On the basis of size, shape, distribution, and staining affinity four types of neurosecretory cells were described in the brain and two types of neurons were also described in the suboesophageal ganglion and circumoesophageal connectives. A minority of neurons in the brain respond to the paraldehyde fuchsin staining technique (PAF) but they differ from each other with respect to the degree of their staining affinity. PAF-positive neurons were not observed in the suboesophageal ganglion and circumoesophageal connectives. Furthermore, no neurohaemal organ was observed in the brain.