Microdetermination of dry mass content in the uterine fluid of four species of viviparous sharks (Squalus acanthias, Carcharhinus plumbeus, Mustelus canis and Rhizoprionodon terraenovae)

Abstract

We describe a micromethod for the determination of dry mass content and wet weight in small (⩾ 20 μl) samples of shark uterine (periembryonic) fluid using a volumetric micropipette and electrobalance. Periembryonic fluid and maternal blood plasma from pregnant specimens of the viviparous sharks Squalus acanthias, Carcharhinus plumbeus, Mustelus canis and Rhizoprionodon terraenovae were analyzed for dry mass content. Values for dry mass (mg/ml), fluid density (g/ml) and percent dry mass are calculated for the periembryonic fluids and maternal blood plasmas of each species. These results are discussed in relation to the dry mass content of periembryonic fluids in other viviparous sharks.