Identity and location of the central neural ganglia in the apple snail Pomacea canaliculata

GIRAUD BILLOUD, M; CROCCE, CC; CASTRO-VAZQUEZ, A

Mendoza

Congreso; XXXI Reunión Anual de la Sociedad de Biología de Cuyo; 2013

Sociedad de Biología de Cuyo

Early authors reported that the central nervous system of this snail is formed by rings of interconnected ganglia around the gut. Six ganglion pairs can be distinguished: bucal, cerebral, pedal, pleural, intestinal and visceral, whose precise location was not clear in those early studies. Notwithstanding, recent authors have only mentioned a ring formed by two cerebral and two pedal ganglia. This apparent contradiction was explored by microdissections and 3D-rendering based on serial sections. The five first ganglion pairs were within the peripharyngeal sinus, while the sixth one was in the visceral hump. The bucal pair was on the surface of the pharyngeal bulb, while the cerebral one was at the tentacles? base. Both pedal ganglia were beneath the bulb, and joined the pleural ganglia in posterior direction on both sides. However, the intestinal pair was asymmetrical: it was continuous with the pleural ganglion on the right, while was separate on the left and communicated with the left pleural ganglion through a long connective. The right intestinal ganglion (subintestinal) also communicates with the left one (supraintestinal) through a commissure passing over the pharyngeal bulb, behind the salivary glands. The posterior connectives of the intestinal ganglia leave the peripharyngeal sinus to enter the visceral hump where they join the fused visceral pair, which lies on the posterior esophagus. These clarifications are significant for further studies of neuronal activation in response to environmental and immune challenges.