Chemical composition of uterine fluid in four species of viviparous sharks ( Squalus acanthias, carcharhinus plumbeus, mustelus canis and rhizoprionodon terraenovae)

Abstract

1. 1. Uterine fluid and blood plasma samples from pregnant specimens of the viviparous sharks Squalus acanthias, Carcharhinus plumbeus, Mustelus canis and Rhizoprionodon lerraenovae were analysed for total protein, total lipid, total glucose and osmolarity. 2. 2. Intracapsular uterine fluids of the matrotroph, Rhizoprionodon terraenovae, whose embryos bear appendiculae, exhibit higher concentrations of protein, lipid and glucose than those of placenta! matrotrophs lacking appendiculae. 3. 3. In near-term specimens R. terraenovae, intracapsular protein and lipid levels in excess of those within the maternal blood plasma suggest active concentration of these molecules within intracapsular fluids. 4. 4. There exists a significant osmotic differential between maternal blood plasma and intracapsular uterine fluid in both R. terraenovae and M. canis. 5. 5. These results are discussed in relation to the evolution of maternal-embryonic transfer mechanisms in viviparous sharks.