The cerebral ganglia of Pomacea canaliculata (Caenogastropoda, Ampullariidae).

MOTUCA ME, GAMARRA-LUQUES C, CASTRO-VAZQUEZ A.

Mendoza

Congreso; XXIII Reunión Anual de la Sociedad de Biología de Cuyo.; 2005

Sociedad de Biología de Cuyo

The cerebral ganglia are flattened paired structures located at the base of tentacles in the peripharyngeal sinus. Both ganglia are joined dorsally by a ribbon-like intercerebral commissure, and they are connected anteriorly with the buccal ganglia, and posteriorly with both the pedopleural ganglia and the visceral ganglia. Nerves of varying thickness, presumably composed of both afferent and efferent fibers, enter/leave the ganglionic borders, while a prominent tentacular nerve enters/leaves at the center of their  dorsolateral aspect. The nerves originating on the ganglionic borders include the optic and otic nerves (on the posterior border) and the labial nerves (on the anterior border). Most neurons in the cerebral ganglia are located both in the ganglionic cortex and in the surroundings of ependymal canaliculi that penetrate the ganglionic medulla. No hemolymphatic vessels penetrate the ganglia. Cortical neurons are either large polyhedral cells, with peripheral Nissl’s bodies and clear nucleolated nuclei, or small, elongated and heavily basophilic cells located mainly around the nerves’ origin. The ependymal canaliculi are surrounded by small polyhedral neurons, with their nuclei close to the ependymal lumen. Also, some large pyriform neurons may be seen either isolated or in small groups in the ganglionic medulla.  Because of their neuronal composition and connections we consider the cerebral ganglia (together with the pleural ganglia) as the first order analyzer-integrator systems of the incoming environmental information.