Sex hormones in Strombus pugilis (Mollusca: Gastropoda) in different gonadal stages

Sex hormones play an essential role in sexual differentiation, maintenance of sexual characteristics, gamete maturation, and mating behavior. However, very little is known about their dynamics in molluscs. We conducted a study on sex hormone (17 beta-estradiol, testosterone, and progesterone) concentrations in male and female Strombus pugilis to identify their variations at different gonadal stages. A total of 90 organisms (30 per month) were collected in February, September, and November 2016. The gonadal digestive gland complex of each specimen was dissected and divided into two sections. One section was set in alcoholic Bouin's fluid and processed with classic histological techniques; the second was macerated with 80% ethanol to extract steroids and analyzed by enzyme immunoassays. Histological section analysis was used to classify gonadal development into three stages: gametogenesis, mature, and undifferentiated. Mature females were observed in September. Testosterone and 17 beta-estradiol concentrations in both sexes were highest in the mature stage. In S. pugilis, 17 beta-estradiol, progesterone, and testosterone were all present, with higher concentrations associated with reproductive activity.