Gametogenic cycle of Mesodesma donacium in Hornitos (II Región), Chile, May 2005 to April 2007

Parameters: Gonad stage: number of male or female clams in each of the following gonad stages: preactive; active; spawned; cytolysed. Collected clams were fixed in formalin and processed later in the laboratory using standard methods (Romeis 1989), embedding gonad tissue in paraplast wax after dehydration. Gonad tissue samples were always taken equally distant between the digestive gland and the proximal end of the foot. Two distinct slides (15mm length, 8mm whidth, 5 µm thik) were analyzed and no differences in gonad developement were observed between slides. Tissue slides were stained with hematoxylin-eosin. Gonad stages were classified following Delgado & Defeo (2007) for Donax hanleyanus.