Development of the male and female genital system in Pomacea canaliculata (Ampullariidae)

GAMARRA-LUQUES C, GIRAUD-BILLOUD M, CASTRO-VAZQUEZ A.

Córdoba, Argentina

Congreso; XXV Reunión Científica Anual de la Sociedad de Biología de Cuyo.; 2007

Sociedad de Biología de Cuyo

The ampullariid genital system is formed by two sets of structures: (1) the gonoduct; and (2) the primordial copulatory apparatus, internally attached to the right mantle edge, and which is present in both sexes. How these primordia differentiate post-hatching in either the male or female structures (including the gonads) is unknown. Newly hatched (2 mm) juveniles have a sexually undifferentiated gonoduct and no copulatory primordium. The latter appears in 5 mm juveniles, when it is of similar size in all individuals.  The proximal (visceral) part of the gonoduct differentiates in either the testis or the ovary in 10 mm juveniles, while the copulatory primordium stays of similar size in both sexes. In the 15 mm stage, the copulatory apparatus is definitely larger in males, and shows all the adult components, though not yet fully developed. In this stage also, the distal (pallial) gonoduct has differentiated either in the prostate/seminal vesicle continuum or in the uterine gland and vagina. All the adult structures are present in 20 mm snails, but the copulatory apparatus remains vestigial in females. Full gonoductal development is reached in 25 mm snails of both sexes, but the copulatory structures remain vestigial in females.