Lung structures for gas exchange and hemopoiesis in Pomacea canaliculata (Architaenioglossa, Ampullariidae).

RODRIGUEZ, C; VEGA, I.A.; ALFREDO JUAN CASTRO VAZQUEZ

San Juan

Congreso; 2° Reunión Conjunta de las Sociedades de Biología de la República Argentina; 2011

Ampullariid snails have both a gill and a lung, which allows them a certain degree of amphibious life. The lung is a flattened pouch ventilated through a siphon, and three distinct tissue arrangements can be recognized in its wall: (1) a fibromuscular and vascular structure (about 1 µm thick) occupying most of the roof of the lung, which is heavily loaded with hemocytes and may serve hemopoiesis; (2) a massive layer (about 3 µm thick) of urate-storing tissue which forms all of the floor and part of the roof of the lung pouch; and (3) a thin (about 1 µm) vascular lamina wholly covering the inner surface of the pouch, i.e., both the roof and the floor structures, which may serve gas exchange and is in contact with air. The hemopoietic structure is a complex arrangement of both muscular and connective tissue fibers, with intersped groups of glycogen-storing cells and hemocyte nodules. The urate-storing structure is made by urocytes radially arranged around large vessels (i.e., as perivascular urate tissues found in other organs of this snail). The gas-exchange structure is formed by a single layer of capillary-like vessels, which are also in tight contact to each other, and which cover the entire inner surface, being in direct contact with air contained in the lung pouch. A more detailed study involving 3-D reconstruction of the lung structures possibly serving hemopoiesis and gas exchange is in progress in our laboratory.