Histology of the central nervous system of the squid, Illex illecobrosus illecobrosus (Leseur)

Bellows, Carlton George (1968) Histology of the central nervous system of the squid, Illex illecobrosus illecobrosus (Leseur). Masters thesis, Memorial University of Newfoundland.

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Abstract

This thesis describes the microscopic structure of the central nervous system of the squid Illex illecebrosus illecebrosus (Lesueur), and relates it to that of other cephalopods. Organs of secretion associated with the brain are also shown together with the results of histochemical tests used to detect the presence of carbohydrates, proteins lipids and nucleic acids. -- The central nervous system of Illex is basically similar to the brains of other cephalopods. It consists of eight interconnected ganglia, some of which are divided into distinct lobes. The cerebral ganglion, situated above the esophagus, contains the association and higher motor centres of the brain, and its neurons are much smaller than the cells in the subesophageal masses. Directly below it and broadly connected to it by the anterior and posterior basal - subesophageal connectives on both sides of the esophagus lies the middle subesophageal mass which is the major source of nerves arising from the brain. The posterior subesophageal mass is separated from the middle mass by a curtain of connective tissue and has several divisions. Nerves from this ganglion innervate the mantle, fins, viscera and chromatophores. The peduncle and olfactory lobes are situated above and posterior to the optic tract. The anterior subesophageal mass, or brachial ganglion, which is separated from the central brain mass and lies just posterior and ventral to the buccal mass, innervates primarily the arms. The superior and inferior buccal ganglia are located above the anterior subesophageal mass. -- Small neurosecretory cells of two types occur in clusters within the tissue of the posterior subesophageal mass, adjacent to small blood sinuses. The components of both the optic glands and parolfactory vesicles were negative to neurosecretory stains. The colloid of the parolfactory vesicles was shown to be a mucoprotein or glycoprotein, containing little cysteine.

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