The Production of beta 1-specific pregnancy glycoprotein (SP1) by the amnion.

Using indirect immunofluorescence, beta 1-specific pregnancy glycoprotein (SP1) was localised to the amnion cells, as well as to trophoblastic cells. Cultures of fragments of amnion incubated with 3H-leucine for up to 72 h demonstrated that protein was synthesized by the amnion. Using antisera specific to SP1 it was shown that after 72 h incubation about 50% of the total protein could be precipitated. These studies demonstrate that the amnion cells are actively involved in the synthesis of SP1 and could account for the high level of this glycoprotein in amniotic fluid.